feat(commit-and-push-self): use llm to generate commit messages

- skip commit if no staged changes
- fallback to timestamp-based message if llm not available
- parse llm output as title + body (first line + lines after blank line)

,commit-and-push-self

@@ -1,6 +1,16 @@
 #!/usr/bin/env bash
-set -e
 
 git add -A
+
+if [ -z "$(git status --porcelain)" ]; then
+  exit 0
+fi
+
+if command -v llm &>/dev/null; then
+  COMMIT_MSG=$(git diff --staged | awk 'BEGIN{print "根据代码变更生成一个 git commit，尽量简洁不废话，如果有正文需要符合标题+空行+正文的规范。只返回结果"}1' | llm)
+  git commit -m "$(echo "$COMMIT_MSG" | head -n1)" -m "$(echo "$COMMIT_MSG" | tail -n +3)"
+else
   git commit -m "auto commit at $(date '+%Y-%m-%d %H:%M:%S')"
+fi
+
 git push