Setup CI workflow and remove obsolete documentation

- Added .github/workflows/ci.yml for automated testing on push/PR
- Removed BLUEPRINT.md and TESTING.md as they are no longer needed
- Verified no references to deleted files exist in the codebase
- Ensured package-lock.json is clean
- Verified tests pass locally

Author: google-labs-jules[bot]

.github/workflows/ci.yml

@@ -0,0 +1,28 @@
+name: CI
+
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+    branches: [ main, master ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [18.x, 20.x]
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+        cache: 'npm'
+    - run: npm ci
+    - run: npm run lint
+    - run: npm run build
+    - run: npm test