Initial MVP: local visual novel library with Ren'Py → PGVN converter

- FastAPI backend: admin bootstrap with forced credential change, admin-created
  users with one-time generated passwords, roles as permission sets
- Games and versions with content-addressed blob storage; forks copy only the
  manifest, so mods share assets with the original
- Worker: archive/RPA extraction, unrpyc for .rpyc, own .rpy parser, Python
  subset translated via ast, media converted to WebP/Opus/WebM
- React panel (library search, game page, upload, users, roles) and a
  framework-free web player with saves, history, skip/auto, transitions
- docker compose: postgres, backend, worker, nginx on a single HTTP port

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/app/db.py

@@ -0,0 +1,18 @@
+from collections.abc import AsyncIterator
+
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+from sqlalchemy.orm import DeclarativeBase
+
+from app.config import get_settings
+
+engine = create_async_engine(get_settings().database_url, pool_pre_ping=True)
+SessionLocal = async_sessionmaker(engine, expire_on_commit=False)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+async def get_session() -> AsyncIterator[AsyncSession]:
+    async with SessionLocal() as session:
+        yield session