feat: re-review on post-approval changes, container improvements

- Compare git HEAD at reviewer approval vs owner finalize to detect
  new code changes after DONE verdict. Re-trigger reviewer if changed,
  complete if unchanged (commit-only is fine).
- Record approved HEAD in source_ref when reviewer says DONE
- Add pnpm store mount, pre-flight checks, idle timeout for containers
- Clean up orphaned containers on shutdown

src/container-runner.ts

@@ -87,7 +87,13 @@ function detectPnpmStorePath(workspaceDir: string): string | null {
     /* pnpm not available */
   }
   // Fallback to default location
-  const defaultStore = path.join(os.homedir(), '.local', 'share', 'pnpm', 'store');
+  const defaultStore = path.join(
+    os.homedir(),
+    '.local',
+    'share',
+    'pnpm',
+    'store',
+  );
   if (fs.existsSync(defaultStore)) return defaultStore;
   return null;
 }