dash: a manual Refresh control

The dashboard polls: `refreshStats()` (`src/doberman/dash/app.py:408`) every 5 s and `refreshPending()` (`:546`) every 2 s, both from `setInterval`. After you approve something elsewhere you wait out the interval with no way to force it. **What to do** 1. Add a small `Refresh` button in the `Recent decisions` header row (`` at line 274), not in `.topbar-right` (see heads-up below). 2. On click call `refreshStats(); refreshPending();`. Both exist and are safe to call any time; no new endpoint. 3. Test in `tests/unit/test_dash_polish.py`: the served shell contains the button markup. Heads-up: two dashboard PRs are in flight (#401 strictness-mode control, #415 per-project title); both edit `dash/app.py`'s top bar. Branch from a fresh `main` and expect a small rebase if they land while you work.