Localization stages 2-3: drafts, publishing, translation editor

- games.main_version_id, version visibility (draft/published) and kind
  (original/translation/mod), version_history; migration 0002
- permissions translations.edit and versions.publish
- "Translate" creates a translation draft; publishing merges the changed
  languages into the main version in place (players keep their saves), the
  previous manifest goes to the history and can be restored
- translation API: overview with per-state stats, entries with filters,
  search and scene context, save, glossary, locale font, PO/CSV export/import
- translation editor page: languages and progress, lines and strings,
  filters, autosave, approve/outdated/fuzzy actions, glossary highlighting,
  "play from here" with the scene restored
- player: ?lang= and ?at= from the editor, per-locale font

(models.py and permissions.py for this landed earlier in 9ee3e1f)

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

backend/app/main.py

@@ -8,7 +8,7 @@ from app.blobs import BLOB_ID_RE, blob_path
 from app.bootstrap import bootstrap
 from app.config import get_settings
 from app.db import SessionLocal
-from app.routers import auth, games, roles, users, versions
+from app.routers import auth, games, i18n, metadata, roles, users, versions
 
 logging.basicConfig(level=logging.INFO)
 
@@ -24,7 +24,7 @@ async def lifespan(_: FastAPI):
 
 app = FastAPI(title="pgames-manager", lifespan=lifespan, docs_url="/api/docs",
               openapi_url="/api/openapi.json")
-for r in (auth, users, roles, games, versions):
+for r in (auth, users, roles, games, versions, i18n, metadata):
     app.include_router(r.router)