feat(ui): slop-band calibration card on the analytics dashboard

[JSONbored]

Add one analytics card visualizing slop-band calibration (predicted slop band vs realized merge/close outcome) from the stats feed. Single card; read-only.

Deliverables

• New SlopBandCalibrationCard typed to the slop-band fields of StatsPayload (src/review/stats.ts)
• Per-band rows (label + predicted count + realized outcome rate) using Stat / MiniSparkbar primitives
• Show bands not raw scores (respect the public/private boundary: never render gittensor.credibility raw)
• Wire into apps/gittensory-ui/src/routes/app.analytics.tsx
• Vitest test: all-bands-present, one-empty-band, and no-data (both ternary arms)

References

• src/review/stats.ts:165
• apps/gittensory-ui/src/components/site/control-primitives.tsx:164
• 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-2297