feat: add git diff capture and session log collection to concurrent runner

- Add git diff capture after each run, saved as diff.patch
- Add session log collection from ~/.qwen/projects/{id}/chats/
- Store session logs in outputs/{run_id}/chats/ with original filename
- Add session_id field to track chat recording UUID
- Modify cwd in session logs to actual runner working directory
- Remove stdout_file/stderr_file from top-level, keep only in prompt_results
- Rename logs folder to openai-logs
- Add File Writer task example for testing file creation

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

.gitignore

@@ -63,3 +63,6 @@ patch_output.log
 docs-site/.next
 # content is a symlink to ../docs
 docs-site/content
+
+# python cache
+__pycache__/