feat(middleware): expose complete React commit timeline

[avocado-cb]

Description

Adds an additive commits field to the React agent stopProfiling result. The field contains every captured commit in chronological order with:

• root and commit identifiers
• render, effect, and passive-effect durations
• timestamp and priority
• rendered-fiber and updater counts
• change-description availability

The existing duration-ranked, size-limited topSlowCommits field remains unchanged for backward compatibility and quick scouting. The React agent documentation and middleware release plan are updated alongside the implementation.

Related Issue

Closes #462

Context

stopProfiling currently exposes only the slowest commits, even though the normalized React DevTools profile retains the full recording. Downstream performance analysis needs the complete timeline to correlate render bursts and post-process the same commit metadata available to profiler tooling.

The timeline is sorted by timestamp, then root id and commit index for deterministic ordering across roots. A regression test covers ordering, metadata, and preservation of the existing slow-commit summary.

Testing

• pnpm checks:affected
• pnpm test:affected
• pnpm release:plan
• Pre-push repository-wide lint and typecheck hooks