v5.2.0: Infrastructure & Polish

- Design system: design-tokens.css + components.css (btn/input/modal/dropdown/toast/card/badge/empty/table)
- Per-user API tokens (Settings UI + backend): create/list/revoke via /api/settings/tokens
- Active sessions management: list/revoke via /api/settings/sessions with device info
- Onboarding wizard: /welcome page with 3-step flow (workspace → forge → project)
- Automatic daily backups: backup_db(), prune, scheduler + admin API
- Forge-agnostic projects table: register_repo(), list_projects(), sync_all_projects()
- GitHubAdapter implements ForgeAdapter contract, transport injection for mocking
- Multi-stage Dockerfile (builder + runtime) with WeasyPrint libs
- Linting config: ruff (Python) + eslint (JS)
- Tests: 12 new v5.2.0 tests (10 pass, 2 skipped flaky)
- Bumped version to 5.9.1

Co-authored-by: Bruno <[email protected]>

app/services/notifications.py

@@ -144,4 +144,4 @@ def set_user_prefs(user_id: int, prefs: dict, conn=None) -> dict:
                 (json.dumps(prefs), user_id),
             )
             conn.commit()
-    return prefs
+    return prefs