Handle transient git fetch failures gracefully

Exit cleanly instead of crashing so the next cron run retries.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deploy_cron.py

@@ -97,7 +97,11 @@ Push a fix to `main` — the cron (every 5 min) will retry automatically on the
 
 
 def main():
-    git('fetch', 'origin', 'main')
+    try:
+        git('fetch', 'origin', 'main')
+    except subprocess.CalledProcessError as exc:
+        print(f'git fetch failed (transient?): {exc} — skipping this run.', file=sys.stderr)
+        return
     remote_sha = git('rev-parse', 'origin/main')
 
     last_sha    = read(SHA_FILE)