chore: Halkyon Learn moves into apps/learn

Its server, client, app and curator, and the tools that write its
assets (maps, Anki fixtures, icons), as they are; paths are fixed in
the commits that follow.

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/learn/halkyon_learn_server/pubspec.yaml

@@ -0,0 +1,61 @@
+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:
+  clock: ^1.1.3
+  crypto: ^3.0.7
+  # What every Halkyon server has (ADR 0014): signing in, the account and its
+  # deletion, pruning, the instance's basics. A Serverpod module in
+  # halkyon_shared, pinned to a signed commit of its main; for local work on
+  # both, a git-ignored pubspec_overrides.yaml at the workspace root points it
+  # at a checkout.
+  halkyon_base_server:
+    git:
+      url: https://code.halkyon.app/project-halkyon/halkyon_shared.git
+      path: packages/halkyon_base_server
+      ref: 96f2d1461803599bdf5b14783f4b3d3a2810742f
+  # Reads the pages profile links point to, for their rel="me" back-links.
+  html: ^0.15.6
+  # Mails email sign-in's codes over SMTP (ADR 0010).
+  mailer: ^7.2.0
+  serverpod: 4.0.4
+  serverpod_auth_idp_server: 4.0.4
+  serverpod_offline_sync_server: 0.0.10
+dev_dependencies:
+  serverpod_test: 4.0.4
+  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