feat: add concurrent runner for batch CLI execution

Add a Python-based concurrent runner that executes multiple Qwen CLI tasks
across different models in parallel using isolated git worktrees.

Features:
- Execute N tasks × M models concurrently with configurable concurrency
- Create isolated git worktrees for each run under ~/.qwen/worktrees
- Real-time progress display with Rich library
- Capture stdout, stderr, and OpenAI API logs per run
- Atomic JSON tracking of all runs with status and metadata
- Automatic cleanup of worktrees after each run

Structure:
- runner.py: Main implementation with asyncio
- requirements.txt: Python dependencies
- README.md: Documentation and usage
- config.example.json: Configuration template
- examples/: Toy example with sample config and project

Usage:
  python runner.py config.json

Each run creates an isolated output directory:
  outputs/{run_id}/
    ├── stdout.txt
    ├── stderr.txt
    └── logs/openai-*.json

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

integration-tests/concurrent-runner/requirements.txt

@@ -0,0 +1,2 @@
+rich>=13.0.0
+aiofiles>=23.0.0