feat(ui): finding acceptance-rate card (did the contributor act on it)

[JSONbored]

Render the finding acceptance-rate signal (a finding was posted inline and the contributor acted on it → merged) as a single analytics card. UI-only card consuming the acceptance payload; backend acceptance computation is tracked separately in #1967 — this bounty is the display slice and assumes the acceptance shape is present on the dashboard payload (guard for absence).

Deliverables

• New AcceptanceRateCard rendering acceptance rate as a % Stat plus accepted/total counts
• Graceful 'not yet available' EmptyState when the acceptance field is absent from the payload (state-views.tsx:86)
• StatusPill quality banding for the rate; window-days label
• Wire into apps/gittensory-ui/src/routes/app.analytics.tsx
• Vitest test: present-with-data, present-zero, and absent (undefined) branches

References

• src/review/outcomes-wire.ts
• apps/gittensory-ui/src/components/site/state-views.tsx:86
• apps/gittensory-ui/src/routes/app.analytics.tsx

Part of #1967.

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📸 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> |

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size: S · held for later release (gittensor:feature once activated)

[linear-code]

JSO-2298