fix: skip pre-push checks on branch deletion

The pre-push hook runs lint/typecheck/test/build checks on every push,
including `git push origin --delete <branch>`. Branch deletion does not
push any code, so verification checks are unnecessary and block the
delete operation.

Detect deletion pushes by reading stdin (local sha is all zeros for
deletes) and exit early.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/codex-git-hooks/pre-push

@@ -16,6 +16,20 @@ if ! git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
   exit 0
 fi
 
+# Skip checks for branch deletion pushes (e.g., git push origin --delete <branch>).
+# The pre-push hook receives lines on stdin: <local ref> <local sha> <remote ref> <remote sha>.
+# For deletions, the local sha is the zero OID.
+is_delete_only=true
+while read -r _local_ref local_sha _remote_ref _remote_sha; do
+  if [[ "$local_sha" != "0000000000000000000000000000000000000000" ]]; then
+    is_delete_only=false
+    break
+  fi
+done
+if [[ "$is_delete_only" == "true" ]]; then
+  exit 0
+fi
+
 ran_any_check=0
 
 log() {