Automatic knowledge lifecycle + resilience

- Scope-aware ranking in get_context (F1)
- Confidence auto-movement: +0.05 on surface, -0.03 decay, auto-archive below 0.2 (F2)
- Auto-consolidation trigger on record_lesson (F3)
- Auto-graduation to copilot-instructions.md at 0.75 confidence / 5 sessions (F4)
- last_surfaced_at exposed in project_query (F5)
- Un-graduation: archived graduated items removed from instructions file
- FTS5 resilience: migration rebuild + runtime auto-recovery on Error 11
- Schema v5: vestigial session_count column removed
- CQS split: GetContext (pure read) / GetContextAndTrack (tracked read)
- DomainService extraction for domain orchestration
- Correctness fixes: Graduate atomicity, MarkUseful overflow, Import NPE, FTS5 crash on quotes

Add release workflow and update README with download instructions

GitHub Actions builds win-x64, linux-x64, osx-arm64 on tag push.
Pre-built binaries attached to GitHub Releases automatically.

Co-authored-by: Copilot <[email protected]>