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/migrations/script.py.mako

@@ -0,0 +1,21 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}