feat: Execute zone - Playwright PC Web + Appium mobile + AI screenshot diff + test conclusion reports

- Add 3 new agents: web-executor, mobile-executor, result-reporter
- web-executor: Playwright multi-browser (Chromium/Firefox/WebKit) automated scripts
- mobile-executor: Appium dual-platform (Android/iOS) automated scripts
- result-reporter: pixel-level AI visual comparison + test conclusion report with screenshots
- Auto-generate executable Python test scripts from Markdown test cases
- Screenshot strategies: on-failure (default) + on-step (optional)
- Visual diff grading: <1% pass / 1-5% minor / 5-15% UI_DIFF / >15% blocker
- Failure multi-classification: REAL_BUG/UI_DIFF/ENV_ISSUE/DATA_ISSUE/CASE_BUG/SCRIPT_ERROR
- requirements.txt: add playwright + Pillow
- Fleet now: 17 agents across 6 battle zones

docs/USER_GUIDE.md

@@ -96,6 +96,20 @@ Fleet 会自动完成：文档解析 → 知识激活 → 需求分析 → 冲
 
 执行到设计战区结束。产出测试策略、测试点、测试用例、测试数据。
 
+### `/qe-fleet execute` — 自动化测试执行
+
+```text
+/qe-fleet execute source_docs/requirements_raw/需求.docx
+```
+
+执行自动化测试：生成 Playwright (PC Web) + Appium (移动端) 脚本，采集截图，AI 视觉对比，输出测试结论报告。
+
+**产出**:
+- `output/execution/{需求名}/playwright_tests.py` — PC Web 自动化脚本
+- `output/execution/{需求名}/appium_tests.py` — 移动端自动化脚本
+- `output/screenshots/{需求名}/` — 截图证据目录
+- `output/execution/{需求名}_执行报告.md` — 含截图对比的测试结论
+
 ### `/qe-fleet review` — 仅评审
 
 ```text
@@ -151,7 +165,7 @@ Fleet 会自动完成：文档解析 → 知识激活 → 需求分析 → 冲
 ### 3.1 标准流程
 
 ```
-需求文档 → PREPARE → ANALYZE → [人工确认] → DESIGN → REVIEW → [质量裁决] → EXPORT
+需求文档 → PREPARE → ANALYZE → [人工确认] → DESIGN → EXECUTE → REVIEW → [质量裁决] → EXPORT
 ```
 
 ### 3.2 确认门禁