feat(ui): maintainer repo/org quality dashboard

[JSONbored]

Parent roadmap: #525
Parent phase: #528

Background

The maintainer panel is thin (install health + a reviewability list). Maintainers want quality trends they can scan.

Goal

A real repo/org quality dashboard: queue health, slop/duplicate trends over time, gate outcomes, top contributors by quality band.

Current Behavior

operator-dashboard.ts surfaces installation counts / recommendation quality, not slop/duplicate/gate-outcome trends or contributor quality bands.

Desired Behavior

• New src/services/maintainer-quality-dashboard.ts mirroring operator-dashboard.ts; mostly read+shape over existing snapshots (buildQueueTrendReport, weekly-value-report.ts, collision clusters, gate-outcome audit events).
• Enrich GET /v1/app/maintainer-dashboard; render sections in apps/gittensory-ui.

Implementation Requirements

• Read snapshots, do not recompute heavy signals on load; show generatedAt + a stale flag.

Public/Private Output Boundaries

• Maintainer/operator-authenticated; still bands not raw numbers; never gittensor.credibility raw or any reward/wallet field.

Acceptance Criteria

• Dashboard shows trends + gate outcomes scoped to the maintainer's repos; UI evidence (screenshots) attached.

Testing Requirements

• npm run test:ci, 97%+ coverage. Service shaping tests + access-scope tests + redaction tests.

[JSONbored]

Reclassified as owner-led visual work (assigned to @JSONbored). This is not a Gittensor-scored contributor task — visual/UI changes are handled by the maintainer to keep review tractable. Forthcoming visual-PR auto-review tooling (before/after screenshots) will make such changes reviewable. Roadmap: #525.