feat(infra): added codeql workflow file

.github/workflows/codeql-analysis.yml

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+name: "CodeQL"
+
+on:
+  push:
+    branches: [ "main" ]
+    paths:
+      - 'src/**'
+      - 'tests/**'
+      - '.github/workflows/codeql-analysis.yml'
+  pull_request:
+    branches: [ "main" ]
+    paths:
+      - 'src/**'
+      - 'tests/**'
+      - '.github/workflows/codeql-analysis.yml'
+  schedule:
+    - cron: '30 18 * * 1' # Runs every Monday at 18:30 UTC
+
+# Centralize the Python version here for easy updates
+env:
+  PYTHON_VERSION: '3.12'
+
+permissions:
+  contents: read
+  security-events: write
+  actions: read
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    timeout-minutes: 36
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'python' ]
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v6
+
+    - name: Set up Python ${{ env.PYTHON_VERSION }}
+      uses: actions/setup-python@v6
+      with:
+        python-version: ${{ env.PYTHON_VERSION }}
+
+    - name: Setup uv
+      uses: astral-sh/setup-uv@v7
+      with:
+        enable-cache: true
+        cache-dependency-glob: "uv.lock"
+
+    - name: Install dependencies
+      run: uv sync --frozen --group github-action
+
+    # Updated to v4 to avoid deprecation of v3 in late 2026
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v4
+      with:
+        languages: ${{ matrix.language }}
+        # Extended suites catch more complex vulnerabilities and code quality smells
+        queries: security-extended,security-and-quality
+        # Explicitly set the source root to ensure Python files are picked up
+        source-root: src
+
+    # Updated to v4 to match initialization
+    - name: Perform Analysis
+      uses: github/codeql-action/analyze@v4
+      with:
+        category: "/language:${{matrix.language}}"

changelog.d/164.infra.rst

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+Integrated GitHub CodeQL for automated security scanning and data-flow analysis of Python source code.