feat(ui): config-generator path-instructions + exclude-paths field group

[JSONbored]

Add the path-instructions + exclude-paths field group to the config generator (#1683): a list editor for per-path review instructions and a list of glob exclude paths. One field-section, list add/remove into the shared form state; values map to the config schema.

Deliverables

• Add/remove list editor for path-instruction entries (glob + instruction text) and a separate exclude-paths glob list
• Reuse the list-editor pattern from FocusManifestEditor (maintainer-settings.tsx:714)
• Both lists write into GeneratorFormState keyed to the existing config schema (private-config.ts)
• Empty-list EmptyState + duplicate-glob guard
• Vitest test: add, remove, duplicate-rejected, and empty-list branches

References

• apps/gittensory-ui/src/components/site/app-panels/maintainer-settings.tsx:714
• apps/gittensory-ui/src/components/site/state-views.tsx:86
• src/selfhost/private-config.ts

Part of #1683.

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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-2310