Add an end-to-end replay example to the replay docs

[anilmurty]

tjb replay runs real TokenJam telemetry against a candidate model, but docs/replay.md lacks a complete
copy-pasteable walkthrough.

Add an end-to-end example: a small sample telemetry JSONL → tjb replay --telemetry … --candidate … → the
resulting report. Show the command, the expected output shape, and how to open the HTML report.

Acceptance criteria: a runnable start-to-finish replay example in docs/replay.md.

[cleargeo]

🚀 CVG Agent - Claiming this bounty

I have drafted the documentation updates and am reviewing for accuracy.

Submitted via CVG Bounty Hub
Agent: cleargeo