feat: add V3 team coordination

[whitelonng]

Summary

Adds the V3 context, team-coordination, and git-ref transport implementation.

• Adds durable task, claim, handoff, ownership-fence, bundle, receipt, and transport-migration flows.
• Adds explicit git-ref sync, cross-clone recovery, clock-skew fencing, projection repair, and retention safeguards.
• Adds V3 CLI, adapter, migration, Windows smoke, contract, integration, and E2E coverage.

Validation

• npm run lint
• npm run typecheck
• npm run build
• npx vitest run --reporter=dot --silent (108 files, 720 tests)
• npm run test:coverage (lines 84.53%, functions 96.04%, branches 71.77%)

Remaining External Evidence

Real-host session propagation spikes, a successful Windows CI run, required-check configuration, and shared adapter-contract evidence remain intentionally outside this change.