Refactor and improve code quality

- Extract repeated patterns into utility functions
- Modularize query handlers into separate files
- Add TypeScript interfaces and type definitions
- Improve error handling with better context
- Add retry logic for transient Elasticsearch errors
- Externalize ES version compatibility configuration
- Add validation utilities
- Add GitHub Actions workflow for multi-version testing
- Add comprehensive documentation (API.md, ES9-COMPATIBILITY.md)
- Improve type safety throughout codebase

Author: marshallswain

.github/workflows/test-matrix.yml

@@ -0,0 +1,65 @@
+name: Test Matrix
+
+on:
+  push:
+    branches: [ main, master, dove ]
+  pull_request:
+    branches: [ main, master, dove ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [18, 20]
+        elasticsearch-version: ['8.15.0', '9.0.0']
+
+    name: Node ${{ matrix.node-version }} - ES ${{ matrix.elasticsearch-version }}
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v3
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Start Elasticsearch ${{ matrix.elasticsearch-version }}
+      run: |
+        docker run -d \
+          --name elasticsearch \
+          -p 9200:9200 \
+          -e "discovery.type=single-node" \
+          -e "xpack.security.enabled=false" \
+          -e "xpack.security.enrollment.enabled=false" \
+          docker.elastic.co/elasticsearch/elasticsearch:${{ matrix.elasticsearch-version }}
+
+    - name: Wait for Elasticsearch
+      run: |
+        for i in {1..30}; do
+          if curl -s "http://localhost:9200/_cluster/health" > /dev/null 2>&1; then
+            echo "Elasticsearch is ready"
+            break
+          fi
+          echo "Waiting for Elasticsearch..."
+          sleep 5
+        done
+
+    - name: Install dependencies
+      run: npm ci
+
+    - name: Build
+      run: npm run build
+
+    - name: Run tests
+      run: |
+        ES_VERSION=${{ matrix.elasticsearch-version }} \
+        ELASTICSEARCH_URL=http://localhost:9200 \
+        npm run mocha
+
+    - name: Upload coverage
+      if: matrix.node-version == '20' && matrix.elasticsearch-version == '8.15.0'
+      uses: codecov/codecov-action@v3
+      with:
+        file: ./coverage/lcov.info