ci: add security scanning workflow

Add automated security checks:
- pip-audit for known vulnerabilities in dependencies
- CodeQL static analysis for Python code

Runs on:
- Every push and PR to main
- Weekly schedule (Monday 9:00 UTC) for catching new CVEs

Author: jmlweb

.github/workflows/security.yml

@@ -0,0 +1,53 @@
+name: Security
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    # Run weekly on Monday at 9:00 UTC
+    - cron: "0 9 * * 1"
+
+jobs:
+  dependency-audit:
+    runs-on: ubuntu-latest
+    name: Dependency Audit
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install pip-audit
+          pip install .
+
+      - name: Run pip-audit
+        run: pip-audit --strict --progress-spinner off
+
+  codeql:
+    runs-on: ubuntu-latest
+    name: CodeQL Analysis
+    permissions:
+      security-events: write
+      actions: read
+      contents: read
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: python
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v3
+        with:
+          category: "/language:python"