Inline the trace parser, modernise the event classifier, add three new analyses

[soulgalore]

• Replace the unmaintained @sitespeed.io/tracium dependency (extracted from Lighthouse circa 2017, last release 0.3.3) with an in-tree ESM port at lib/chrome/trace/. computeMainThreadTasks is byte-equivalent so existing result.cpu.{categories,events,urls} consumers see no change.
• Modernise the event classifier. The original list only knew about ~30 event names, so on busy 2026-era pages roughly half the trace fell through to "other" — on a sample cnet run that meant 1.3 s of "other" hiding RunTask, v8.run, IntersectionObserverController::computeIntersections, PrePaint, Commit, Layerize, v8.callFunction, V8.DeserializeContext and friends. The expanded list (drawing from modern Lighthouse + the WebPageTest-derived map in waterfall-tools + direct sampling of real traces) reclassifies ~1.5 s of that "other" into the right buckets. A new groupForEvent() lookup adds prefix matching for V8.GC* so future V8 GC phases auto-classify without enumeration.
• Add three new analyses on result.cpu, each independently computed and wrapped in its own try/catch so a bug in one can't poison the existing payload:
  • scriptCosts — Lighthouse-style per-URL parse / compile / execute / total breakdown.
  • forcedReflows — Layout / UpdateLayoutTree events nested under JS-driven tasks (EventDispatch, FunctionCall, TimerFire, FireAnimationFrame, …) with the script that triggered each.
  • nonCompositedAnimations — Animation events whose compositeFailed bitmask is non-zero, with the unsupported properties.

Co-authored-by: Claude Opus 4.7 (1M context) noreply@anthropic.com
Change-Id: I085d3ef2bd32bcf663c6b764d1551c59a544a165