[FEP-0069] FlagRelease multi-version pipeline tracking

## Summary

Tracking issue for [FEP-0069](https://github.com/flagos-ai/community/blob/main/fep/sig-tools/0069-flagrelease-multi-version-pipeline.md) — FlagRelease Multi-Version Automated Migration & Release Pipeline (sig-tools, `Implementable`, Target Version: FlagOS 2.2, supersedes FEP-0012). FEP merged in #69.

## Open items (blocking `Implementable` → `Implemented`)

- [ ] **flagos-ai/FlagRelease#20 merged** — the consolidated implementation PR (dual-branch routing, V1–V4 multi-version release, accuracy hard gate / performance non-blocking, synthetic performance baseline, anti-drift gates).
- [ ] **Test Plan rows flipped to Implemented** — all seven verification rows are currently Pending, verified in flagos-ai/FlagRelease#20; update them (and the FEP Status) via a follow-up PR once that PR merges.
- [ ] **Related PRs updated** as any further implementation PRs land.

## Schedule

Per [#47](https://github.com/flagos-ai/community/issues/47) / `release/2.2/schedule.md`: implementation code lands by **Code Freeze 2026-08-31**; testing window runs to 09-24.

## References

- FEP PR: #69
- Implementation PR: https://github.com/flagos-ai/FlagRelease/pull/20
- Superseded FEP: [FEP-0012](https://github.com/flagos-ai/community/blob/main/fep/sig-tools/0012-flagrelease-automated-migration.md)
- Release tracking: #47

Check flagos-ai/FlagRelease#20 and the FEP-0069 document at fep/sig-tools/0069-flagrelease-multi-version-pipeline.md first. Once the implementation PR merges, update the seven Test Plan rows and the FEP Status, then update related PR references as further implementation PRs land.

Written by the indexing model from the issue text.