feat: add Agent Monitor oven

[alowpoly]

Summary

• add the declarative Agent Monitor Oven, capture/reprojection engine, CLI wiring, and live dashboard route
• turn retained agent events into readable categories, exact DIFF patches, filter tabs, truthful filtered counts, and a work-rhythm timeline
• extend the closed Oven vocabulary and shared renderers without adding runtime dependencies, while preserving Review Loops behavior from current main

Verification

• npm run verify — 964 core tests and all auxiliary suites passed; Streaming Diff 13/13; Dashboard/Oven 240/240
• npm run build:dashboard
• live Agent Monitor browser checks: filtered counts, empty state, pagination, zero horizontal overflow, clean console