feat(oauth): import favoris/abos Google (YouTube) et Twitch vers abonnements/likes
- Backend: server/oauth.mjs (auth URL, echange code, refresh, fetch
subscriptions/likes Google, follows Twitch), table oauth_connections
+ migration, routes /api/oauth/:provider/{url,callback,preview,import},
/api/oauth/{status,connections}
- Front: /library/import (connect, preview, import), service
oauth-import, lien depuis Abonnements
- Config: GOOGLE_CLIENT_ID/SECRET/REDIRECT_URI, TWITCH_REDIRECT_URI,
OAUTH_APP_BASE_URL documentes (.env.example, docker-compose),
passthrough docker-compose.local.yml, roadmap README cochee