feat: add bugfix workflow, test-engineer agent, and debugging skills

- Add test-engineer agent for bug reproduction and verification
- Add /qc:bugfix command for structured bugfix workflow
- Add e2e-testing skill covering headless/interactive modes, MCP testing
- Add structured-debugging skill for hypothesis-driven debugging
- Simplify AGENTS.md to focus on essential commands and conventions
- Add terminal-capture scenario for bugfix workflow testing
- Add .qwen folder to ESLint ignore list

Known limitations: The /qc:bugfix workflow and e2e-testing skill
are experimental and may be unstable or consume significant tokens.

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

.qwen/skills/e2e-testing/references/mcp-testing.md

@@ -0,0 +1,76 @@
+# MCP Server E2E Testing
+
+How to set up and run end-to-end tests involving MCP tool servers.
+
+## Where MCP Config Goes
+
+MCP servers are configured in `.qwen/settings.json` under `mcpServers`. This is
+the **only** location that works for E2E testing.
+
+Common mistakes that waste time:
+
+- `.mcp.json` — Claude Code convention, not Qwen Code
+- `settings.local.json` — the JSON schema validation rejects `mcpServers` here
+- `--mcp-config` CLI flag — does not exist
+
+## Setup
+
+The CLI needs a git repo to load project settings. Create a temp directory:
+
+```bash
+mkdir -p /tmp/test-dir && cd /tmp/test-dir && git init -q
+mkdir -p .qwen
+cat > .qwen/settings.json << 'EOF'
+{
+  "mcpServers": {
+    "my-server": {
+      "command": "node",
+      "args": ["/tmp/my-mcp-server.js"],
+      "trust": true
+    }
+  }
+}
+EOF
+```
+
+Run from that directory:
+
+```bash
+cd /tmp/test-dir && <qwen> "prompt" \
+  --approval-mode yolo --output-format json
+```
+
+## Writing Test Servers
+
+Use `scripts/mcp-test-server.js` as a template. It's a zero-dependency
+JSON-RPC server over stdin/stdout — no npm install needed.
+
+To create a server with custom tools, copy the template and edit the
+`TOOL_DEFINITIONS` array and the `handleToolCall` function. Each tool definition
+follows the MCP `inputSchema` format (standard JSON Schema).
+
+### Sanity-checking the server
+
+Test the server without the CLI by piping JSON-RPC directly:
+
+```bash
+node /tmp/my-mcp-server.js << 'EOF'
+{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}
+{"jsonrpc":"2.0","method":"notifications/initialized"}
+{"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}
+EOF
+```
+
+## Verifying the Server Loaded
+
+Check the `type: "system"` init message in JSON output:
+
+```json
+"mcp_servers": [{"name": "my-server", "status": "connected"}]
+```
+
+If `mcp_servers` is empty:
+
+- You're not running from the directory containing `.qwen/settings.json`
+- The directory is not a git repo (`git init` missing)
+- The server command/path is wrong (check stderr with `2>&1`)