Initial project setup

Add project structure with package.json, source code, tests, documentation, and GitHub workflows.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/build.yml

@@ -0,0 +1,156 @@
+name: Build and Test YT2AI Bookmarklet
+
+on:
+  push:
+    branches: [ main, develop ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+    
+    strategy:
+      matrix:
+        node-version: [16.x, 18.x, 20.x]
+    
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      
+    - name: Setup Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+        cache: 'npm'
+        
+    - name: Install dependencies
+      run: npm ci
+      
+    - name: Run linting
+      run: npm run lint
+      
+    - name: Check code formatting
+      run: npm run format:check
+      
+    - name: Run tests
+      run: npm run test:coverage
+      
+    - name: Build development version
+      run: npm run build:dev
+      
+    - name: Build production version
+      run: npm run build
+      
+    - name: Verify build artifacts
+      run: |
+        echo "Checking build artifacts..."
+        ls -la dist/
+        echo "Production bookmarklet size:"
+        stat -c%s dist/bookmarklet.min.js
+        echo "Development bookmarklet size:"
+        stat -c%s dist/bookmarklet-debug.js
+        
+    - name: Validate bookmarklet format
+      run: |
+        echo "Validating bookmarklet format..."
+        if grep -q "^javascript:" dist/bookmarklet.min.js; then
+          echo "✓ Production bookmarklet has correct javascript: prefix"
+        else
+          echo "✗ Production bookmarklet missing javascript: prefix"
+          exit 1
+        fi
+        
+        if grep -q "^javascript:" dist/bookmarklet-debug.js; then
+          echo "✓ Debug bookmarklet has correct javascript: prefix"
+        else
+          echo "✗ Debug bookmarklet missing javascript: prefix"
+          exit 1
+        fi
+        
+    - name: Check bundle size limits
+      run: |
+        echo "Checking bundle size limits..."
+        PROD_SIZE=$(stat -c%s dist/bookmarklet.min.js)
+        MAX_SIZE=10240  # 10KB limit
+        
+        if [ $PROD_SIZE -le $MAX_SIZE ]; then
+          echo "✓ Production bundle size OK: ${PROD_SIZE} bytes (limit: ${MAX_SIZE} bytes)"
+        else
+          echo "✗ Production bundle size too large: ${PROD_SIZE} bytes (limit: ${MAX_SIZE} bytes)"
+          exit 1
+        fi
+        
+    - name: Upload build artifacts
+      uses: actions/upload-artifact@v3
+      with:
+        name: bookmarklet-builds-node-${{ matrix.node-version }}
+        path: |
+          dist/
+          coverage/
+        retention-days: 30
+        
+    - name: Upload coverage to Codecov
+      if: matrix.node-version == '18.x'
+      uses: codecov/codecov-action@v3
+      with:
+        file: ./coverage/lcov.info
+        flags: unittests
+        name: codecov-umbrella
+        fail_ci_if_error: false
+
+  release:
+    needs: build-and-test
+    runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main' && github.event_name == 'push'
+    
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+        token: ${{ secrets.GITHUB_TOKEN }}
+        
+    - name: Setup Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: '18.x'
+        cache: 'npm'
+        
+    - name: Install dependencies
+      run: npm ci
+      
+    - name: Build production version
+      run: npm run build
+      
+    - name: Semantic Release
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      run: |
+        git config user.name "github-actions[bot]"
+        git config user.email "github-actions[bot]@users.noreply.github.com"
+        npm run release
+          
+  security-scan:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      
+    - name: Setup Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: '18.x'
+        cache: 'npm'
+        
+    - name: Install dependencies
+      run: npm ci
+      
+    - name: Run security audit
+      run: npm audit --audit-level high
+      
+    - name: Build and scan with CodeQL
+      uses: github/codeql-action/analyze@v2
+      with:
+        languages: javascript