Unify persona reviews with feedback threads

[selfcontained]

Summary

• replace the legacy persona-review lifecycle with the unified reviews and feedback-item thread model
• guide review agents through MCP-based submission, feedback, resolution, and tracked discussion
• migrate existing persona reviews safely and document the assisted-update preflight
• show review sub-agents beneath their parent, derive active review state from submission, and link completed agents to their review
• improve review Markdown rendering, collapsed summaries, interaction accessibility, responsive controls, and theme-token styling
• log best-effort review prompt injection failures with review and recipient context

Validation

• pnpm run check
• pnpm run test — server 2,235 passed / 8 skipped; web 214 passed
• pnpm run test:e2e --workers=1 — 167 passed / 12 expected skips
• focused review handler tests — 13 passed
• live=true end-to-end review-agent flows exercised during implementation

Migration notes

Includes migrations 0032–0034 and update-migrations/0009-unified-reviews-migration.yaml for assisted-update handling and in-flight legacy review preflight.