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/pubspec.yaml

@@ -0,0 +1,47 @@
+name: halkyon_learn_server
+description: Starting point for a Serverpod server.
+# version: 1.0.0
+# homepage: https://www.example.com
+
+environment:
+  sdk: '^3.13.0'
+
+resolution: workspace
+
+dependencies:
+  serverpod: 4.0.0
+  serverpod_auth_idp_server: 4.0.0
+  serverpod_cloud_storage: 4.0.0
+
+dev_dependencies:
+  lints: '>=3.0.0 <7.0.0'
+  serverpod_test: 4.0.0
+  test: ^1.25.5
+
+serverpod:
+  # Companion Flutter apps that `serverpod start` can launch (Ctrl+R), keyed
+  # by a display alias. The default device is the web server, opening the
+  # machine's default browser when ready. All non-reserved properties are
+  # forwarded to `flutter run`. For the best IDE debugging experience, use
+  # `chrome` or a native target as the device. See the example below:
+  #
+  # Admin:
+  #   path: ../apps/admin_flutter
+  #   displayName: "Admin app"
+  #   auto_launch: true
+  #   device: chrome
+  #   target: lib/main.dart
+  #   web-hostname: 0.0.0.0
+  #   web-port: 8090
+  #   release: true
+  #   pub: false
+  #   dart-define:
+  #     API_URL=https://admin.example.com
+  #     FLAVOR=production
+  flutter_apps:
+    halkyon_learn:
+      path: ../halkyon_learn_flutter
+      displayName: "Halkyon learn app"
+      auto_launch: true
+      target: lib/driver.dart
+      device: linux