chore: scaffold the Serverpod 4 build

Deviations from a stock `serverpod create`:
- Dropped Flutter web support, for two reasons:
  - Appflowy editor had issues in the past, potentially related to the
    Flutter-Web IME bridge. Upstream has also open bugs in relation to
that:
    - AppFlowy-IO/appflowy-editor#1029 [Bug][Web] Unwanted space on click
       and overall space bugs (open)
    - AppFlowy-IO/appflowy-editor#782 [Bug] Editor auto-scrolling when
       pressing space too quickly if placed inside a scrollable (open)
  - Offline-first is a required feature. serverpod_offline_sync's SQLite
    support in browsers, maybe via sqlite3.wasm + OPFS, is not
documented.
- SDK constraints raised to ^3.13.0, instead of ^3.12.2, so enjoy the
  newest language features.
- Pinned to Flutter 3.47.4 via FVM.

Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_server/lib/server.dart

@@ -0,0 +1,51 @@
+import 'package:serverpod_auth_idp_server/core.dart';
+import 'package:serverpod_auth_idp_server/providers/email.dart';
+import 'package:serverpod_cloud_storage/serverpod_cloud_storage.dart';
+
+import 'src/generated/serverpod.dart';
+
+/// The starting point of the Serverpod server.
+void run(List<String> args) async {
+  // Initialize Serverpod. The generated Serverpod class is already connected
+  // with your project's generated code.
+  final pod = Serverpod(args);
+
+  // Initialize authentication services for the server.
+  // Token managers will be used to validate and issue authentication keys,
+  // and the identity providers will be the authentication options available for users.
+  pod.initializeAuthServices(
+    tokenManagerBuilders: [
+      // Use JWT for authentication keys towards the server.
+      JwtConfigFromPasswords(),
+    ],
+    identityProviderBuilders: [
+      // Configure the email identity provider for email/password authentication.
+      // The default setup works with Serverpod Cloud without configuration. In
+      // development the verification codes are logged to the console, and in
+      // staging and production they are sent through the Serverpod Cloud email
+      // service. If you want to use a custom provider for sending emails, use
+      // `EmailIdpConfigFromPasswords`.
+      ServerpodCloudEmailIdpConfig(
+        appDisplayName: 'halkyon_learn',
+      ),
+    ],
+  );
+
+  // Configure cloud storage.
+  // This setup works with Serverpod Cloud without extra configuration.
+  // If you want to use a custom provider for cloud storage, replace these
+  // with your preferred provider.
+  pod.addCloudStorage(
+    await ServerpodCloudProvider.private(
+      fallback: () => DatabaseCloudStorage('private'),
+    ),
+  );
+  pod.addCloudStorage(
+    await ServerpodCloudProvider.public(
+      fallback: () => DatabaseCloudStorage('public'),
+    ),
+  );
+
+  // Start the server.
+  await pod.start();
+}