Add codeql workflow

.github/workflows/codeql.yml

@@ -0,0 +1,31 @@
+name: "CodeQL"
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+  schedule:
+    - cron: '24 19 * * 3'
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'javascript', 'python' ]
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v2
+      with:
+        languages: ${{ matrix.language }}
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v2
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v2

.gitignore

@@ -15,3 +15,4 @@ web/node_modules
 web/coverage
 core
 !/web/**/*.ts
+.dccache