Add browser-based unit tests for xiaozhi test modules

- Add browser-compatible test files (no npm required)

  - recorder.test.browser.js: 8 tests for microphone and HTTP detection

  - tools.test.browser.js: 5 tests for Live2D actions and error handling

- Add test runner (test-runner.html) with built-in test framework

- Add null safety checks in tools.js for DOM element access

- Add documentation (English and Chinese versions)

  - README_TESTS.md / README_TESTS_CN.md: Complete test guide

  - QUICK_START_TEST.md / QUICK_START_TEST_CN.md: Quick start guides

- Total: 13 unit tests covering microphone detection, HTTP detection, Live2D actions, and error handling

main/xiaozhi-server/test/QUICK_START_TEST.md

@@ -0,0 +1,44 @@
+# Quick Start - Browser Tests (No npm required!)
+
+## Run Tests in 3 Steps
+
+1. **Start a local server:**
+   ```bash
+   cd main/xiaozhi-server/test
+   python -m http.server 8007
+   ```
+
+2. **Open in browser:**
+   ```
+   http://localhost:8007/test-runner.html
+   ```
+
+3. **Click "▶ Run All Tests"**
+
+That's it! No npm, no package.json, no dependencies needed.
+
+## What Gets Tested?
+
+- ✅ Microphone availability detection (3 tests)
+- ✅ HTTP non-localhost detection (5 tests)  
+- ✅ Live2D action execution (5 tests)
+- ✅ Error handling and edge cases
+
+**Total: 13 unit tests** (8 recorder tests + 5 tools tests)
+
+## Test Files
+
+- `js/core/audio/recorder.test.browser.js` - Audio/recorder tests
+- `js/core/mcp/tools.test.browser.js` - MCP tools and Live2D tests
+
+## Troubleshooting
+
+**Tests don't run?**
+- Make sure you're using a local server (not `file://`)
+- Check browser console for errors
+- Ensure all `.js` files are accessible
+
+**Some tests fail?**
+- Check the error message in the test results
+- Verify mocks are set up correctly
+- Check browser console for detailed errors