feat(online): session compte, stockage sécurisé et adapter API (ticket #64)

Ajoute l'adapter API distant (infrastructure/remote/auth_api.dart,
http_api_client.dart) et le stockage sécurisé du token d'auth
(infrastructure/security/secure_storage_auth_token_store.dart), câblés
dans app_bootstrap.dart. Étend le modèle Drift (migration
schemaVersion 9→10) et la couche application (ports, use cases,
entités) pour la session de compte. flutter pub get OK (ajout http,
flutter_secure_storage), build_runner OK, dart format appliqué,
analyze propre (mêmes infos préexistantes), 109/109 tests verts,
build APK debug validé. Premier ticket du chantier "Ajouter les
features serveur au client" (#63).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pubspec.lock

@@ -374,6 +374,54 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.0.35"
+  flutter_secure_storage:
+    dependency: "direct main"
+    description:
+      name: flutter_secure_storage
+      sha256: "9cad52d75ebc511adfae3d447d5d13da15a55a92c9410e50f67335b6d21d16ea"
+      url: "https://pub.dev"
+    source: hosted
+    version: "9.2.4"
+  flutter_secure_storage_linux:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_linux
+      sha256: be76c1d24a97d0b98f8b54bce6b481a380a6590df992d0098f868ad54dc8f688
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.3"
+  flutter_secure_storage_macos:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_macos
+      sha256: "6c0a2795a2d1de26ae202a0d78527d163f4acbb11cde4c75c670f3a0fc064247"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.3"
+  flutter_secure_storage_platform_interface:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_platform_interface
+      sha256: cf91ad32ce5adef6fba4d736a542baca9daf3beac4db2d04be350b87f69ac4a8
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.2"
+  flutter_secure_storage_web:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_web
+      sha256: f4ebff989b4f07b2656fb16b47852c0aab9fed9b4ec1c70103368337bc1886a9
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.1"
+  flutter_secure_storage_windows:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_windows
+      sha256: b20b07cb5ed4ed74fc567b78a72936203f587eba460af1df11281c9326cd3709
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.2"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -417,7 +465,7 @@ packages:
     source: hosted
     version: "0.15.6"
   http:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: http
       sha256: "87721a4a50b19c7f1d49001e51409bddc46303966ce89a65af4f4e6004896412"
@@ -536,6 +584,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.0.1"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: f2c445dce49627136094980615a031419f7f3eb393237e4ecd97ac15dea343f3
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.7"
   json_annotation:
     dependency: transitive
     description:
@@ -997,6 +1053,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.0.3"
+  win32:
+    dependency: transitive
+    description:
+      name: win32
+      sha256: d7cb55e04cd34096cd3a79b3330245f54cb96a370a1c27adb3c84b917de8b08e
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.15.0"
   xdg_directories:
     dependency: transitive
     description: