build: Android's built-in Kotlin, the three plugins applying KGP themselves patched in third_party/

AGP 9 compiles Kotlin itself (android.builtInKotlin=true in every app),
and warns that applying the Kotlin Gradle Plugin will soon fail.
flutter_web_auth_2 5.1.0, keyboard_height_plugin 0.3.0 and flutter_tts
4.2.5 still apply it unconditionally, so their pub releases are copied
into third_party/ with only their android/build.gradle changed, and
the root overrides them by path (third_party/README.md says when to
drop each). The servers' images copy third_party/, as pub refuses an
override whose path is missing. third_party/ isn't our own code: left
out of the analysis and the format check.

All four apps' APKs build without the warning. A Kotlin daemon's
session file that slipped into Train's android/ goes, and every app's
android/.gitignore keeps .kotlin/ out.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

third_party/flutter_web_auth_2/ios/flutter_web_auth_2.podspec

@@ -0,0 +1,23 @@
+#
+# To learn more about a Podspec see http://guides.cocoapods.org/syntax/podspec.html.
+# Run `pod lib lint flutter_web_auth_2.podspec` to validate before publishing.
+#
+Pod::Spec.new do |s|
+  s.name             = 'flutter_web_auth_2'
+  s.version          = '5.0.0'
+  s.summary          = 'Flutter plugin for authenticating a user with a web service.'
+  s.description      = <<-DESC
+Flutter plugin for authenticating a user with a web service.
+                       DESC
+  s.homepage         = 'https://github.com/ThexXTURBOXx/flutter_web_auth_2'
+  s.license          = { :file => '../LICENSE' }
+  s.author           = { 'Nico Mexis' => 'nico.mexis@kabelmail.de' }
+  s.source           = { :path => '.' }
+  s.source_files = 'flutter_web_auth_2/Sources/flutter_web_auth_2/**/*.swift'
+  s.dependency 'Flutter'
+  s.platform = :ios, '11.0'
+
+  # Flutter.framework does not contain a i386 slice.
+  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
+  s.swift_version = '5.9'
+end

third_party/flutter_web_auth_2/ios/flutter_web_auth_2/Package.swift

@@ -0,0 +1,22 @@
+// swift-tools-version: 5.9
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "flutter_web_auth_2",
+    platforms: [
+        .iOS("11.0")
+    ],
+    products: [
+        .library(name: "flutter-web-auth-2", targets: ["flutter_web_auth_2"])
+    ],
+    dependencies: [],
+    targets: [
+        .target(
+            name: "flutter_web_auth_2",
+            dependencies: [],
+            resources: []
+        )
+    ]
+)

third_party/flutter_web_auth_2/ios/flutter_web_auth_2/Sources/flutter_web_auth_2/FlutterWebAuth2Plugin.swift

@@ -0,0 +1,196 @@
+import AuthenticationServices
+import Flutter
+import SafariServices
+import UIKit
+
+public class FlutterWebAuth2Plugin: NSObject, FlutterPlugin {
+    public static func register(with registrar: FlutterPluginRegistrar) {
+        let channel = FlutterMethodChannel(name: "flutter_web_auth_2", binaryMessenger: registrar.messenger())
+        let instance = FlutterWebAuth2Plugin()
+        registrar.addMethodCallDelegate(instance, channel: channel)
+        registrar.addApplicationDelegate(instance)
+    }
+
+    var completionHandler: ((URL?, Error?) -> Void)?
+
+    public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
+        if call.method == "authenticate",
+           let arguments = call.arguments as? [String: AnyObject],
+           let urlString = arguments["url"] as? String,
+           let url = URL(string: urlString),
+           let callbackURLScheme = arguments["callbackUrlScheme"] as? String,
+           let options = arguments["options"] as? [String: AnyObject]
+        {
+            var sessionToKeepAlive: Any? // if we do not keep the session alive, it will get closed immediately while showing the dialog
+            completionHandler = { (url: URL?, err: Error?) in
+                self.completionHandler = nil
+
+                if (sessionToKeepAlive != nil) {
+                    if #available(iOS 12, *) {
+                        (sessionToKeepAlive as! ASWebAuthenticationSession).cancel()
+                    } else if #available(iOS 11, *) {
+                        (sessionToKeepAlive as! SFAuthenticationSession).cancel()
+                    }
+                    sessionToKeepAlive = nil
+                }
+
+                if let err = err {
+                    if #available(iOS 12, *) {
+                        if case ASWebAuthenticationSessionError.canceledLogin = err {
+                            result(
+                                FlutterError(
+                                    code: "CANCELED",
+                                    message: "User canceled login",
+                                    details: [
+                                        "domain": (err as NSError).domain,
+                                        "code": (err as NSError).code,
+                                        "description": err.localizedDescription
+                                   ]
+                               )
+                            )
+                            return
+                        }
+                    }
+
+                    if #available(iOS 11, *) {
+                        if case SFAuthenticationError.canceledLogin = err {
+                            result(
+                                FlutterError(
+                                    code: "CANCELED",
+                                    message: "User canceled login",
+                                    details: [
+                                        "domain": (err as NSError).domain,
+                                        "code": (err as NSError).code,
+                                        "description": err.localizedDescription
+                                   ]
+                                )
+                            )
+                            return
+                        }
+                    }
+
+                    result(FlutterError(code: "EUNKNOWN", message: err.localizedDescription, details: nil))
+                    return
+                }
+
+                guard let url = url else {
+                    result(FlutterError(code: "EUNKNOWN", message: "URL was null, but no error provided.", details: nil))
+                    return
+                }
+
+                result(url.absoluteString)
+            }
+
+            if #available(iOS 12, *) {
+                var _session: ASWebAuthenticationSession? = nil
+                if #available(iOS 17.4, *) {
+                    if (callbackURLScheme == "https") {
+                        guard let host = options["httpsHost"] as? String else {
+                            result(FlutterError.invalidHttpsHostError)
+                            return 
+                        }
+
+                        guard let path = options["httpsPath"] as? String else {
+                            result(FlutterError.invalidHttpsPathError)
+                            return 
+                        }
+
+                        _session = ASWebAuthenticationSession(url: url, callback: ASWebAuthenticationSession.Callback.https(host: host, path: path), completionHandler: completionHandler!)
+                    } else {
+                        _session = ASWebAuthenticationSession(url: url, callback: ASWebAuthenticationSession.Callback.customScheme(callbackURLScheme), completionHandler: completionHandler!)
+                    }
+                } else {
+                    _session = ASWebAuthenticationSession(url: url, callbackURLScheme: callbackURLScheme, completionHandler: completionHandler!)
+                }
+                let session = _session!
+
+                if #available(iOS 13, *) {
+                    var rootViewController: UIViewController? = nil
+
+                    // FlutterViewController
+                    if (rootViewController == nil) {
+                        rootViewController = UIApplication.shared.delegate?.window??.rootViewController as? FlutterViewController
+                    }
+
+                    // UIViewController
+                    if (rootViewController == nil) {
+                        rootViewController = UIApplication.shared.keyWindow?.rootViewController
+                    }
+
+                    // ACQUIRE_ROOT_VIEW_CONTROLLER_FAILED
+                    if (rootViewController == nil) {
+                        result(FlutterError.acquireRootViewControllerFailed)
+                        return
+                    }
+
+                    while let presentedViewController = rootViewController!.presentedViewController {
+                        rootViewController = presentedViewController
+                    }
+                    if let nav = rootViewController as? UINavigationController {
+                        rootViewController = nav.visibleViewController ?? rootViewController
+                    }
+
+                    guard let contextProvider = rootViewController as? ASWebAuthenticationPresentationContextProviding else {
+                        result(FlutterError.acquireRootViewControllerFailed)
+                        return
+                    }
+                    session.presentationContextProvider = contextProvider
+                    if let preferEphemeral = options["preferEphemeral"] as? Bool {
+                        session.prefersEphemeralWebBrowserSession = preferEphemeral
+                    }
+                }
+
+                session.start()
+                sessionToKeepAlive = session
+            } else if #available(iOS 11, *) {
+                let session = SFAuthenticationSession(url: url, callbackURLScheme: callbackURLScheme, completionHandler: completionHandler!)
+                session.start()
+                sessionToKeepAlive = session
+            } else {
+                result(FlutterError(code: "FAILED", message: "This plugin does currently not support iOS lower than iOS 11", details: nil))
+            }
+        } else if call.method == "cleanUpDanglingCalls" {
+            // we do not keep track of old callbacks on iOS, so nothing to do here
+            result(nil)
+        } else {
+            result(FlutterMethodNotImplemented)
+        }
+    }
+
+    public func application(
+        _ application: UIApplication,
+        continue userActivity: NSUserActivity,
+        restorationHandler: @escaping ([Any]) -> Void) -> Bool
+    {
+        switch userActivity.activityType {
+            case NSUserActivityTypeBrowsingWeb:
+                guard let url = userActivity.webpageURL, let completionHandler = completionHandler else {
+                    return false
+                }
+                completionHandler(url, nil)
+                return true
+            default: return false
+        }
+    }
+}
+
+@available(iOS 13, *)
+extension FlutterViewController: ASWebAuthenticationPresentationContextProviding {
+    public func presentationAnchor(for session: ASWebAuthenticationSession) -> ASPresentationAnchor {
+        return view.window!
+    }
+}
+
+fileprivate extension FlutterError {
+    static var acquireRootViewControllerFailed: FlutterError {
+        return FlutterError(code: "ACQUIRE_ROOT_VIEW_CONTROLLER_FAILED", message: "Failed to acquire root view controller", details: nil)
+    }
+
+    static var invalidHttpsHostError: FlutterError {
+        return FlutterError(code: "INVALID_HTTPS_HOST_ERROR", message: "Failed to retrieve host for https scheme", details: nil)
+    }
+
+    static var invalidHttpsPathError: FlutterError {
+        return FlutterError(code: "INVALID_HTTPS_PATH_ERROR", message: "Failed to retrieve path for https scheme", details: nil)
+    }
+}