Burst populates the strip + hydrate Estimated/Actual after a hard refresh

[aakri0]

Why

Two cost-strip gaps left by #47:

1. Invoke ×50 didn't update Estimated max / Actual. Last 30 days ticked because refreshAll already tracks /usage/cost, but onBurst skipped both renderEstimate and pollResult. The first two cells of the strip were single-submit-only.
2. After a hard refresh, Estimated max and Actual were empty. Their values lived only in JS state set by onSubmit/onBurst. A page reload nuked that, leaving — until the user submitted again.

Fixes

onBurst()

• Calls fetchEstimate(body) → renderEstimate. Estimated max populates immediately with the per-job number (the aggregate lives in Last 30 days where it belongs).
• Clears the Actual cell, then awaits all 50 submits, picks the first job_id and calls pollResult() on it so Actual ticks live for one representative — same UX as a single submit.

hydrateCostStripFromJobs() + computeEstimateLocal()

• On every refreshAll tick, if the strip is empty AND the user hasn't just submitted (lastInvokeAt < 30s), pick the most recent terminal job from /jobs and:
  • render its cost as Actual,
  • reconstruct its worst-case estimate locally using rates cached from /usage/cost.pricing.
• Active flows take priority via state.lastInvokeAt, set in onSubmit and onBurst, so an in-flight pollResult never gets clobbered by hydration.

The local estimate reconstruction mirrors api/pricing.estimate_max_cost exactly (same formula, same per-attempt fee accounting, same network treatment) and reuses the rate card already on /usage/cost.pricing, so the API stays the single source of truth.

Verified

• API /jobs?limit=1 returns every spec field hydration needs (memory_mb, timeout_seconds, max_retries, cpu_nanos, auto_install) plus the structured cost object on terminal rows.
• 174 tests pass.
• New JS shipped: 8 references to hydrateCostStripFromJobs/computeEstimateLocal/lastInvokeAt/results[0] in the served app.js?v=19.

app.js?v=19.