Add CodeQL scanning workflow for Python

Uses the default query suite (not security-extended) and excludes
tests/docs/dist from analysis to keep initial findings low-noise.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: derek73

.github/codeql/codeql-config.yml

@@ -0,0 +1,6 @@
+name: "CodeQL config"
+
+paths-ignore:
+  - tests
+  - docs
+  - dist

.github/workflows/codeql.yml

@@ -0,0 +1,33 @@
+name: CodeQL
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+  schedule:
+    - cron: '30 4 * * 1'
+
+permissions:
+  contents: read
+
+jobs:
+  analyze:
+    name: Analyze (python)
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+
+    steps:
+    - uses: actions/checkout@v7
+
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v3
+      with:
+        languages: python
+        config-file: ./.github/codeql/codeql-config.yml
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v3
+      with:
+        category: "/language:python"