- Created routers/image_studio/models.py with all 40 Pydantic models
- Created routers/image_studio/deps.py with get_studio_manager() and _require_user_id()
- Renamed old monolithic image_studio.py -> image_studio_router.py
- Updated __init__.py to re-export the router for backward compatibility
- Old file now imports models and deps from new modules (no inline definitions)
Backward compatibility: from routers.image_studio import router still works.
Route count unchanged: 33 routes, prefix /api/image-studio.
