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  filters, autosave, approve/outdated/fuzzy actions, glossary highlighting,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>

frontend/src/App.tsx

@@ -8,6 +8,7 @@ import { Login } from "./pages/Login";
 import { NewGame } from "./pages/NewGame";
 import { Play } from "./pages/Play";
 import { Roles } from "./pages/Roles";
+import { TranslationEditor } from "./pages/TranslationEditor";
 import { Users } from "./pages/Users";
 import { useTheme } from "./theme";
 import { Icon } from "./ui/Icon";
@@ -108,6 +109,7 @@ export function App() {
                 <Route path="/" element={<RequirePerm perm="games.play"><Library /></RequirePerm>} />
                 <Route path="/games/new" element={<RequirePerm perm="games.upload"><NewGame /></RequirePerm>} />
                 <Route path="/games/:gameId" element={<RequirePerm perm="games.play"><GamePage /></RequirePerm>} />
+                <Route path="/versions/:versionId/translate" element={<RequirePerm perm="games.play"><TranslationEditor /></RequirePerm>} />
                 <Route path="/admin/users" element={<RequirePerm perm="users.manage"><Users /></RequirePerm>} />
                 <Route path="/admin/roles" element={<RequirePerm perm="roles.manage"><Roles /></RequirePerm>} />
                 <Route path="/account" element={<ChangeCredentials />} />