icône: manette de jeu (flutter_launcher_icons) au lieu du logo Flutter

Ajoute flutter_launcher_icons (manette blanche sur fond indigo, adaptatif +
legacy) et l'étape CI de génération après flutter create/pub get.

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

.gitea/workflows/build.yml

@@ -28,6 +28,7 @@ jobs:
           flutter create --platforms=android --org nfteam --project-name gamemanager .
           python3 tool/patch_android.py
           flutter pub get
+          dart run flutter_launcher_icons
           flutter build apk --release --build-name="${NAME}" --build-number="${RUN}"
           cp build/app/outputs/flutter-apk/app-release.apk gamemanager.apk
           printf '{"version":"1.0.%s","version_code":%s,"notes":"Build CI #%s"}' "${RUN}" "${RUN}" "${RUN}" > version.json