Smart Gmail Job Correspondence Integration Progress

Branch

Created separate Gmail feature branch.
Captured foundation context in .gsd/milestones/M006/M006-CONTEXT.md.
Planned milestones M006-M010 for the Gmail workstream.
Planned slice M006/S01.
Confirmed existing architecture seams:
- Gmail OAuth/token flow already exists.
- Per-job Gmail candidate search/import/thread refresh already exists.
- Correspondence persistence already stores Gmail thread/message metadata.
- Current implementation is job-local, not global-inbox/review oriented.
Implemented M006/S01 foundation changes:
- durable Gmail sync-state fields on GmailConnection
- SQLite/MySQL bootstrap support for new Gmail sync-state columns
- richer GET /api/gmail/status response
- per-job correspondence UI now shows sync diagnostics
- focused backend/frontend Gmail tests added and passing
- Phase 2 extension seam scaffolded with a no-op enrichment service
- Phase 1/2 design doc added at docs/gmail-correspondence-phase1.md
Started M007 ingestion/storage work:
- imported correspondence now stores direction, Gmail labels JSON, and attachment metadata JSON
- Gmail message detail extraction now reads labels and attachment metadata from Gmail payloads
- focused Gmail backend/frontend tests pass against the richer import contract

Implement M006/S01/T01: refactor Gmail connection foundation and sync-state model.
Implement M006/S01/T02: expose sync-state surfaces in UI without breaking current correspondence workflow.
Implement M006/S01/T03: prepare Phase 2 extension seam/docs.
Verify backend + frontend Gmail focused tests.
Commit and push incremental progress.

Previous CV/parsing branch work is separate and already pushed.
Local dev SQLite runtime still has missing-table drift in some unrelated surfaces (RuleSettings, Companies, etc.); avoid conflating that with the Gmail feature work.
Existing per-job Gmail tests live in JobTrackerApi.Tests/GmailControllerTests.cs and job-tracker-ui/src/correspondence-gmail-import.test.tsx.