feat(todo): the app on halkyon_app, with its own icon

Todo's app is halkyon_app's instance and session gates with Todo's
frame ("Todo" under "Halkyon", its icon, its own sentences) and an
instance check accepting only `todo`; TodoDependencies on an instance,
an empty TodoPerson per person, nothing kept or synced yet. A person
sees an empty home and their account: whose it is on which instance,
switching account, signing out and deleting it (each asking first where
it deletes), and About with the source of what the instance runs and
the licence list. Texts in British English and German. App ID
app.halkyon.todo on every platform, GitHub's callback scheme registered
on Android, no web build.

Its icon is Lucide's list-checks (lucide-static 1.50.0) in the brand's
blues on white: tool/app_icons.py draws its strokes with Pillow and
writes every platform's launcher icon; Lucide's ISC notice joins the
licence list.

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

apps/todo/halkyon_todo_flutter/android/app/build.gradle.kts

@@ -5,7 +5,7 @@ plugins {
 }
 
 android {
-    namespace = "com.example.halkyon_todo_flutter"
+    namespace = "app.halkyon.todo"
     compileSdk = flutter.compileSdkVersion
     ndkVersion = flutter.ndkVersion
 
@@ -16,7 +16,7 @@ android {
 
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
-        applicationId = "com.example.halkyon_todo_flutter"
+        applicationId = "app.halkyon.todo"
         // You can update the following values to match your application needs.
         // For more information, see: https://flutter.dev/to/review-gradle-config.
         minSdk = flutter.minSdkVersion

apps/todo/halkyon_todo_flutter/android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,9 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- The app talks to its instance: release builds need this too (Flutter's
+         template grants it to debug and profile builds only). -->
+    <uses-permission android:name="android.permission.INTERNET"/>
     <application
-        android:label="halkyon_todo_flutter"
+        android:label="Halkyon Todo"
         android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity
@@ -25,6 +28,18 @@
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
+        <!-- Receives GitHub's redirect after signing in (app.halkyon.todo://github-callback). -->
+        <activity
+            android:name="com.linusu.flutter_web_auth_2.CallbackActivity"
+            android:exported="true"
+            android:taskAffinity="">
+            <intent-filter android:label="flutter_web_auth_2">
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <data android:scheme="app.halkyon.todo" />
+            </intent-filter>
+        </activity>
         <!-- Don't delete the meta-data below.
              This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
         <meta-data

apps/todo/halkyon_todo_flutter/android/app/src/main/kotlin/app/halkyon/todo/MainActivity.kt

@@ -0,0 +1,5 @@
+package app.halkyon.todo
+
+import io.flutter.embedding.android.FlutterActivity
+
+class MainActivity : FlutterActivity()

apps/todo/halkyon_todo_flutter/android/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <background android:drawable="@color/ic_launcher_background"/>
+  <foreground>
+      <inset
+          android:drawable="@drawable/ic_launcher_foreground"
+          android:inset="16%" />
+  </foreground>
+</adaptive-icon>

apps/todo/halkyon_todo_flutter/android/app/src/main/res/values/colors.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#ffffff</color>
+</resources>