fix(miner-ui): oldestQueuedAgeMs computed/validated but never displayed, breaking the stated CLI/web-UI shared-data-path contract

[JSONbored]

Context

apps/loopover-miner-ui/src/lib/portfolio-queue.ts:25,50,58 computes and validates oldestQueuedAgeMs. Its own header comment (lines 1-5) states the miner-ui now serves "the SAME per-repo dashboard shape the CLI's queue dashboard command computes ... so the miner-ui and the CLI share one data path." The CLI does render this field (packages/loopover-miner/lib/portfolio-dashboard.js:62, "oldest-queued: Xm"), but neither apps/loopover-miner-ui/src/routes/portfolio.tsx nor routes/index.tsx's OverviewPortfolioCard (lines 71-88) ever reads it — the stated parity claim isn't actually delivered in the web UI.

Requirements

• Render oldestQueuedAgeMs (formatted the same way the CLI does, e.g. "oldest queued: Xm") in either portfolio.tsx or OverviewPortfolioCard (whichever is the more appropriate summary location — check which one already shows the sibling queue-depth/age-adjacent stats).
• Do not change the CLI's own rendering (portfolio-dashboard.js) — it's already correct and is the reference for formatting.
• This is a UI-only change under apps/**.

Deliverables

• oldestQueuedAgeMs is visibly rendered somewhere in the miner-ui portfolio view, matching the CLI's formatting.

Expected Outcome

The web dashboard actually delivers the "shares one data path with the CLI" parity its own code comment claims.

Links & Resources

• apps/loopover-miner-ui/src/lib/portfolio-queue.ts:1-5,25,50,58
• packages/loopover-miner/lib/portfolio-dashboard.js:62 (CLI reference rendering)
• apps/loopover-miner-ui/src/routes/portfolio.tsx, routes/index.tsx:71-88

[linear-code]

JSO-4294