Git operations service using subprocess. Provides commit log, diff, blame, push, clone, pull, fork, and PR creation. Deliberately avoids gitpython/pygit2. Stateless class with all `@staticmethod` methods.
Used by version history endpoint, kb_commit/kb_push MCP tools, CLI git commands, ExportService (export-to-repo), and RepoService (subscribe, fork, sync). See collaboration-services for full method listing.