feat: Add process abort control and improve auth detection

apps/server/src/lib/git.ts

@@ -27,6 +27,9 @@ const logger = createLogger('GitLib');
  *   These are merged on top of the current process environment.  Pass
  *   `{ LC_ALL: 'C' }` to force git to emit English output regardless of the
  *   system locale so that text-based output parsing remains reliable.
+ * @param abortController - Optional AbortController to cancel the git process.
+ *   When the controller is aborted the underlying process is sent SIGTERM and
+ *   the returned promise rejects with an Error whose message is 'Process aborted'.
  * @returns Promise resolving to stdout output
  * @throws Error with stderr/stdout message if command fails. The thrown error
  *   also has `stdout` and `stderr` string properties for structured access.
@@ -39,6 +42,15 @@ const logger = createLogger('GitLib');
  * // Force English output for reliable text parsing:
  * await execGitCommand(['rebase', '--', 'main'], worktreePath, { LC_ALL: 'C' });
  *
+ * // With a process-level timeout:
+ * const controller = new AbortController();
+ * const timerId = setTimeout(() => controller.abort(), 30_000);
+ * try {
+ *   await execGitCommand(['fetch', '--all', '--quiet'], cwd, undefined, controller);
+ * } finally {
+ *   clearTimeout(timerId);
+ * }
+ *
  * // Instead of unsafe:
  * // await execAsync(`git branch -D ${branchName}`, { cwd });
  * ```
@@ -46,13 +58,15 @@ const logger = createLogger('GitLib');
 export async function execGitCommand(
   args: string[],
   cwd: string,
-  env?: Record<string, string>
+  env?: Record<string, string>,
+  abortController?: AbortController
 ): Promise<string> {
   const result = await spawnProcess({
     command: 'git',
     args,
     cwd,
     ...(env !== undefined ? { env } : {}),
+    ...(abortController !== undefined ? { abortController } : {}),
   });
 
   // spawnProcess returns { stdout, stderr, exitCode }