feat(enrichment): PR history analyzer + engine context passthrough

[kiannidev]

Summary

Ship the history analyzer (#1478) in REES and pass the metadata the engine already has (author, body, short-lived GitHub token) through enrichment-wire so historical analysis can run during webhook-triggered reviews.

Behavior

REES history analyzer:

• Parse linked issues from PR body (Fixes #123, Closes org/repo#456)
• When a broker/installation token is present, fetch issue state/title and author merged-PR count in-repo
• Report newcomer vs established author, linked-issue alignment, and missing issue references

Engine passthrough:

• Extend buildReviewEnrichment payload with author, body, baseSha, githubToken
• Resolve installation token in runAiReviewForAdvisory (best-effort, same pattern as grounding/RAG)

Scope

• review-enrichment/src/analyzers/history.ts + types/render/brief wiring
• src/review/enrichment-wire.ts + src/queue/processors.ts
• Tests: review-enrichment/test/ + test/unit/enrichment-wire.test.ts

Acceptance criteria

• Linked issues parsed from PR body
• Author track record fetched when token available; degraded gracefully without
• Engine POST includes new fields; flag-off path unchanged
• Full local gate green with patch coverage