The board's forge strip says 'needs you: forge <text>' when forgeVerdict has something to say #2442

Part 1 of #2324. It changes only the web board, not forgeNeeds or the terminal.

Done looks like:

• [ ] In src/web/pages/board.ts forgeStrip, when forgeVerdict(view, Date.now()) (src/kernel/guard_verdict.ts) returns text, the strip shows one span needs you: forge <text>, sets data-ok="no", and does not show "All fine". When it returns undefined, the strip is the same as today.
• [ ] Nothing else changes: no new key on /healthz, the review and ask counts are unchanged, and src/actions/health.ts is not touched.
• [ ] Tests in test/board.test.ts: a guard view with a held incident shows needs you: forge held: …, and an empty view still shows "All fine". Run bun test test/board.test.ts test/guard-verdict.test.ts and quote the result.