dash: "Copy details" button on each pending-approval card

Each pending-approval card in the dashboard (`renderPending`, `src/doberman/dash/app.py:448-544`) shows the risk badge, summary, expiry, reason codes, explanation and the Approve/Deny buttons, all built with `createElement`/`textContent`. There's no way to grab those fields to paste into a chat or an issue except retyping them. **What to do** 1. In the per-row loop of `renderPending`, add a `Copy details` next to Approve/Deny. 2. On click, `navigator.clipboard.writeText(JSON.stringify({id, tier, risk, action_type, reason_codes, explanation}, null, 2))` built from the row the server sent. Wrap it in `try/catch`, the same defensive shape the file already uses for `sessionStorage` (lines 306-314); the clipboard API is unavailable in some contexts and a failure must not break the card. 3. Only fields `/api/pending` already serves (`_pending_row`, line 755 onward) go into the copied text. Never add a raw target or path; the server redacts for a reason. 4. Test in `tests/unit/test_dash_polish.py`: the served shell contains `btn-copy` (same style as the existing badge-class assertions). 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`, stay out of `.topbar-right`, and expect a small rebase if they land while you work.