Add miner dashboard route consuming /api/ranked-candidates (currently extension-only)

[JSONbored]

Problem

/api/ranked-candidates (backed by packages/loopover-miner/lib/ranked-candidates.js) already exposes a full per-issue discovery breakdown (laneFit/freshness/potential/feasibility/dupRisk) — real, working data — but was built for the browser extension's opportunity badge, and no miner-ui dashboard route consumes it.

Area

apps/loopover-miner-ui/.

Proposal

Add a dashboard route/view consuming /api/ranked-candidates.

⚠️ Required pattern — read apps/loopover-miner-ui/src/routes/run-history.tsx and its vite-*-api.ts backing plugin before starting (or another existing data-driven miner-ui route, if a closer match exists — check the routes directory). The new route's data-fetching, loading-state, and layout conventions must match an existing route, not invent a new fetching/rendering approach.

Deliverables

• A dashboard route rendering /api/ranked-candidates data, matching an existing miner-ui route's exact structural conventions (name the specific route file mirrored, in the PR description).

Test Coverage Requirements

apps/loopover-miner-ui/** — match this package's existing route test conventions.

Resources

• packages/loopover-miner/lib/ranked-candidates.js, /api/ranked-candidates
• apps/loopover-miner-ui/src/routes/run-history.tsx (a concrete existing pattern to mirror)
• Decision: keep, invest in, or remove apps/loopover-miner-extension (opportunity overlay) #7566 (extension keep/kill decision — independent of this, not blocking it)

Boundaries

Read-only view of already-existing data — no changes to the ranking logic itself.

Contributor-eligible. Mirror an existing route's exact conventions — name which one in the PR.

[linear-code]

JSO-5421