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>

integration-tests/concurrent-runner/examples/toy-config.json

@@ -15,12 +15,12 @@
     },
     {
       "id": "task-2",
-      "name": "AGI Prediction",
+      "name": "File Writer",
       "prompts": [
-        "Use shell tool to get current date",
-        "Predict how many dates left until we have AGI (artificial general intelligence)"
+        "Use shell tool to get current date.",
+        "Create a new file called 'counter.txt' with numbers 1 to 10, each on a new line."
       ]
     }
   ],
-  "models": ["qwen3-coder-plus", "kimi-k2.5"]
+  "models": ["qwen3-coder-plus", "claude-sonnet-4-20250514"]
 }