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/formula_engine.py

@@ -1,8 +1,8 @@
 """FlowDeck — Formula Engine (v1.5.0)."""
 from __future__ import annotations
 
-from datetime import datetime, date, timedelta
-from typing import Any, Callable, Optional
+from datetime import date, datetime, timedelta
+from typing import Any, Callable
 
 
 class FormulaEngine:
@@ -214,7 +214,7 @@ class FormulaEngine:
             return val.split("...")[0]
         return val
 
-    def _end(self, ctx: dict, s: Any) -> Optional[str]:
+    def _end(self, ctx: dict, s: Any) -> str | None:
         """Extract end date from a date range."""
         val = str(s)
         if "..." in val: