Persist Guided Reviews across sessions

[alexanderkreidich]

Summary

• persist Guided Review output, generation settings, and per-section Reviewed state across server sessions
• isolate artifacts by canonical repository + PR/MR or branch, while reusing them across reliably matched hosted and local head branches
• retain stale guides with an explicit Outdated warning and regeneration action; failed regeneration leaves the prior guide intact
• keep Bun and Pi review server behavior in parity and document the durable workflow

Testing

• bun test — 2246 passed
• DOM_TESTS=1 bun test packages/review-editor/components/guide/GuideScreen.test.tsx packages/review-editor/components/guide/GuideSectionCard.test.tsx
• bun run typecheck
• bun run build:pi
• bun run build:opencode
• bun run build:marketing
• compiled standalone Plannotator binary
• independent review: openai-codex/gpt-5.6-sol — PASS

Closes #1112

[alexanderkreidich]

Closing because #1112 has already been implemented and closed.