refactor(infra): cull unused infrastructure and file cache helpers

src/project_manager.py

@@ -87,15 +87,6 @@ def get_git_commit(git_dir: str) -> str:
  except Exception:
   return ""
 
-def get_git_log(git_dir: str, n: int = 5) -> str:
- try:
-  r = subprocess.run(
-   ["git", "log", "--oneline", f"-{n}"],
-   capture_output=True, text=True, cwd=git_dir, timeout=5,
-  )
-  return r.stdout.strip() if r.returncode == 0 else ""
- except Exception:
-  return ""
   # ── default structures ───────────────────────────────────────────────────────
 
 def default_discussion() -> dict[str, Any]: