fix(ci): generate stub files before flutter analyze

The generated/ directory (app_config.dart, theme_colors.dart) is created
by build_whitelabel.py from theme.json. Since theme.json is not in the
repo, the lint gate fails on missing generated imports.

Added ci_stub_gen.py to produce minimal stubs so flutter analyze passes
before the whitelabel build step. Wired into all jobs in ci.yml and
release.yml.

.gitea/workflows/ci.yml

@@ -36,6 +36,10 @@ jobs:
       - name: Install dependencies
         run: flutter pub get
 
+      - name: Generate stubs (lint gate support)
+        if: hashFiles('theme.json') == ''
+        run: python3 ci_stub_gen.py
+
       - name: Analyze Dart code
         run: flutter analyze --fatal-warnings
 
@@ -61,6 +65,9 @@ jobs:
       - name: Install dependencies
         run: flutter pub get
 
+      - name: Generate stubs (lint gate support)
+        run: python3 ci_stub_gen.py
+
       - name: Run tests
         run: flutter test --reporter=expanded
 
@@ -116,9 +123,12 @@ jobs:
           python -m pip install --upgrade pip
           pip install -r requirements.txt
 
-      - name: Install Flutter dependencies
+      - name: Install dependencies
         run: flutter pub get
 
+      - name: Generate stubs (lint gate support)
+        run: python3 ci_stub_gen.py
+
       - name: Analyze (gate before build)
         run: flutter analyze --fatal-warnings