Resolves add/add conflict in diff-cache.ts (kept typed PhaseMetaResponse/
FileDiffResponse interfaces from HEAD over unknown-typed singletons from test
branch) and content conflict in phase.ts (kept both phaseMetaCache and
fileDiffCache imports; removed auto-merged duplicate firstClone/headHash/
cacheKey/cached declarations and unreachable empty-projects guard).
Also cleans auto-merged duplicate getHeadCommitHash in orchestrator.test.ts
and simple-git-branch-manager.ts.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>