feat(replays): Add replay timeline inspector

[sentry-junior]

Add a catalog-only inspect_replay_timeline tool that reconstructs timestamped replay activity so agents and clients can explain what happened around an error or frustrating interaction.

Structured Timeline Contract

The tool declares an output schema and returns structured-only results with replay identity, availability status, applied filters, pagination counts, and typed timeline events. Each event carries absolute and replay-relative timestamps plus typed key/value details; compatibility text is generated by the MCP server.

Focused Inspection

Callers can filter by event category, focus on an absolute timestamp window, and cap the returned timeline. Archived and segmentless replays use the same stable output shape with an explicit status and unavailable reason.

Project constraints remain enforced, replay recording failures remain visible, and the tool stays catalog-only behind the existing replay capability.

[sentry-warden]

aroundTimestamp Date.parse NaN silently filters all timeline events

Date.parse is not guarded for NaN, so valid-ISO but unparsable timestamps silently filter out all events.

Evidence

• aroundTimestamp passes z.string().datetime({ offset: true }) validation, but Date.parse can still return NaN for valid-format but out-of-range dates (e.g., "0000-01-01T00:00:00Z").
• aroundMs is assigned Date.parse(params.aroundTimestamp) without a Number.isNaN check (line 209).
• The window filter Math.abs(event.timestampMs - aroundMs) <= windowMs evaluates to NaN <= windowMs, which is always false (line 221).
• Every event is excluded and the caller receives an empty events array with no error or warning.
• parseTimestamp(replay.started_at) in the same file correctly guards against NaN at line 425–426, showing the expected pattern was omitted for aroundTimestamp.

_{Identified by Warden · code-review · E2J-4UD}