Add comprehensive test suite for Color Palette Generator

- Create test.html with 20 automated tests
- Cover color generation, palette management, locking, storage, and UI
- Include custom test framework with assertions
- Add detailed test documentation in README.md
- Tests validate all core functionality from PR #34

Author: GitHub Copilot CLI

webapp/tests/README.md

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+# Color Palette Generator - Test Suite
+
+Comprehensive test suite for the Color Palette Generator web application.
+
+## Running Tests
+
+### Browser Tests (Recommended)
+
+Open `test.html` in a web browser:
+
+```bash
+# From the webapp/tests directory
+open test.html  # macOS
+xdg-open test.html  # Linux
+start test.html  # Windows
+```
+
+Or use a local server:
+
+```bash
+# From the webapp directory
+python -m http.server 8000
+# Then navigate to http://localhost:8000/tests/test.html
+```
+
+The tests will run automatically when the page loads. You can also click the "Run All Tests" button to re-run them.
+
+## Test Coverage
+
+### 1. Color Generation (3 tests)
+- ✓ Validates hex color format generation
+- ✓ Ensures randomness in color generation
+- ✓ Validates color name generation
+
+### 2. Palette Generation (4 tests)
+- ✓ Confirms 5 colors are generated
+- ✓ Validates palette structure (hex + name)
+- ✓ Checks DOM element creation
+- ✓ Verifies hex code display formatting
+
+### 3. Color Locking (3 tests)
+- ✓ Tests lock toggle functionality
+- ✓ Validates unlock functionality
+- ✓ Ensures locked colors persist across regenerations
+
+### 4. Palette Storage (4 tests)
+- ✓ Tests saving to localStorage
+- ✓ Validates saved palette structure
+- ✓ Tests loading saved palettes
+- ✓ Verifies clear functionality
+
+### 5. UI Interactions (4 tests)
+- ✓ Copy indicator visibility
+- ✓ Saved palettes display/hide logic
+- ✓ Lock icon state changes
+- ✓ UI element updates
+
+### 6. Hex Color Validation (2 tests)
+- ✓ Validates hex color range (0x000000 to 0xFFFFFF)
+- ✓ Ensures proper padding of hex values
+
+## Test Framework
+
+The test suite uses a custom lightweight test framework that includes:
+
+- **Test Runner**: Organizes and executes test suites
+- **Assertions**: Comprehensive assertion library
+- **Async Support**: Handles asynchronous operations
+- **Visual Feedback**: Real-time test results with pass/fail indicators
+- **Summary Statistics**: Overview of test execution
+
+## Assertions Available
+
+```javascript
+assert.equals(actual, expected, message)
+assert.true(value, message)
+assert.false(value, message)
+assert.exists(value, message)
+assert.isType(value, type, message)
+assert.matches(value, regex, message)
+assert.greaterThan(actual, expected, message)
+assert.arrayLength(array, length, message)
+assert.includes(container, value, message)
+```
+
+## Test Structure
+
+Each test suite follows this pattern:
+
+```javascript
+runner.suite('Suite Name', ({ test }) => {
+    test('test description', async () => {
+        // Test implementation
+        const appWindow = await loadApp();
+        // Assertions
+        assert.equals(actual, expected);
+    });
+});
+```
+
+## Key Features Tested
+
+1. **Core Functionality**
+   - Random color generation
+   - Palette initialization
+   - Color locking mechanism
+
+2. **Persistence**
+   - LocalStorage integration
+   - Save/load operations
+   - Clear functionality
+
+3. **User Interface**
+   - DOM manipulation
+   - Event handling
+   - Visual feedback
+
+4. **Data Validation**
+   - Hex color format
+   - Color range validation
+   - Palette structure
+
+## Expected Results
+
+All tests should pass when the Color Palette Generator is functioning correctly. The test summary will show:
+
+- Total tests: 20
+- All tests should pass (green)
+- Duration: typically under 500ms
+
+## Troubleshooting
+
+### Tests Not Running
+
+1. Ensure you're accessing `test.html` via a web server or `file://` protocol
+2. Check browser console for any errors
+3. Verify `../index.html` path is correct relative to test file
+
+### Test Failures
+
+If tests fail, check:
+
+1. The main `index.html` file has all required functions
+2. localStorage is enabled in your browser
+3. The app initializes correctly in an iframe
+
+### Cross-Browser Testing
+
+This test suite has been designed to work in:
+- Chrome/Edge (latest)
+- Firefox (latest)
+- Safari (latest)
+
+## Continuous Integration
+
+To integrate these tests into a CI/CD pipeline, consider using:
+
+- **Playwright**: For headless browser testing
+- **Puppeteer**: For Chrome-based automated testing
+- **Selenium**: For multi-browser testing
+
+Example Playwright test runner:
+
+```javascript
+const { chromium } = require('playwright');
+
+(async () => {
+  const browser = await chromium.launch();
+  const page = await browser.newPage();
+  await page.goto('file://path/to/tests/test.html');
+  await page.waitForTimeout(2000);
+  const failed = await page.locator('#failed-tests').textContent();
+  await browser.close();
+  process.exit(parseInt(failed) === 0 ? 0 : 1);
+})();
+```
+
+## Future Enhancements
+
+Potential additions to the test suite:
+
+- [ ] Clipboard functionality tests
+- [ ] Keyboard shortcut tests (SPACE key)
+- [ ] Animation timing tests
+- [ ] Accessibility tests
+- [ ] Performance benchmarks
+- [ ] Visual regression tests
+- [ ] Edge case handling (invalid colors, storage limits)
+
+## Contributing
+
+When adding new features to the Color Palette Generator:
+
+1. Add corresponding tests to this suite
+2. Ensure all existing tests still pass
+3. Update this README with new test coverage
+4. Follow the existing test structure and naming conventions