Add a live Ask (RAG) box to the agents page

[JSONbored]

POST /api/v1/ask is grounded RAG Q&A over the registry (Vectorize + Workers AI llama-3.1-8b, live probe health injected), but agents.tsx:83 only shows it as a curl snippet. Add a real 'Ask' box on the agents page that POSTs a question and renders the grounded answer. Maintainer-leaning because it 503s when AI is off and is AI-rate-limited, so it needs graceful degradation and the AI-availability call is the maintainer's.

Deliverables

• Add an askQuestion mutation/query in queries.ts (or a small client helper) that POSTs { question } to /api/v1/ask with the 4096B body cap enforced
• Add an Ask box UI to agents.tsx (input + submit + answer render), reusing existing typography/section components
• Gracefully degrade when /api/v1/ask returns 503 ai-off (show the curl fallback + a notice; do not error the page)
• Debounce/disable submit to respect AI_RATE_LIMITER; show a loading state while the model responds
• Add unit tests for the request shape (body cap), the ai-off 503 branch, and the answer-render branch

References

• repo/workers/api.mjs:3056 (handleAskRequest, 503 when AI off, body cap 4096B)
• repo/src/ai-search.mjs (askQuestion RAG)
• repo-ui/src/routes/agents.tsx:83 (curl snippet only)
• repo-ui/src/lib/metagraphed/client.ts (apiFetch for POST)

---

📸 Required: before/after screenshots (this is a UI change)

Non-negotiable. PRs that change UI must include a before/after screenshot table. PRs without it are automatically closed — no exceptions.

Rules:

• Show every page/feature you changed — before and after, one row each.
• Use the markdown table below. Screenshots go inside the table only — no large full-size images pasted elsewhere in the PR.
• Each cell is a clickable thumbnail (a small image linking to the full-size image) with a one-line caption underneath.
• Upload screenshots to the PR by drag-and-drop (GitHub hosts them on its CDN). Do NOT commit image files to the repo.

Copy this and fill it in (replace FULL_IMAGE_URL with the URL GitHub gives you after you drop the image in):

| Page / Feature | Before | After |
|---|---|---|
| `/your-route` | [<img src="FULL_IMAGE_URL" width="260">](FULL_IMAGE_URL)<br><sub>before: short caption</sub> | [<img src="FULL_IMAGE_URL" width="260">](FULL_IMAGE_URL)<br><sub>after: short caption</sub> |

---

---

size: M · maintainer-only (owner)

[linear-code]

JSO-2078