task_age() crashed with ValueError when created_at contained the
literal format string '%s' instead of a Unix timestamp, taking down
the entire GET /board endpoint with a 500.
- Add _safe_int() helper that returns None on non-numeric values
- Refactor task_age() to use _safe_int instead of bare int() casts
- Wrap task_age() call in _task_dict with try/except fallback so one
corrupt row never kills the whole board endpoint
061a183008