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/config.example.json

@@ -0,0 +1,34 @@
+{
+  "concurrency": 3,
+  "yolo": true,
+  "source_repo": ".",
+  "worktree_base": "~/.qwen/worktrees",
+  "outputs_dir": "./outputs",
+  "results_file": "./results.json",
+  "tasks": [
+    {
+      "id": "code-review",
+      "name": "Security Code Review",
+      "prompts": [
+        "Review the codebase for security vulnerabilities.",
+        "Focus on input validation, authentication, and data handling."
+      ]
+    },
+    {
+      "id": "refactor",
+      "name": "Refactoring Suggestions",
+      "prompts": [
+        "Analyze the code structure and suggest refactoring improvements.",
+        "Prioritize changes that improve maintainability and performance."
+      ]
+    },
+    {
+      "id": "docs",
+      "name": "Documentation Generation",
+      "prompts": [
+        "Generate comprehensive API documentation for the main modules."
+      ]
+    }
+  ],
+  "models": ["claude-3-5-sonnet-20241022", "qwen3-coder-plus"]
+}