fix(ci): add custom CodeQL workflow to replace expensive default setup

The default CodeQL setup runs all 45 Python security queries against the
entire codebase. Two queries (CleartextLogging, PolynomialReDoS) produce
result sets > 2 GiB, causing 49+ minute runs that fail and block CI.

- Add custom workflow with 30-minute timeout and concurrency limits
- Exclude py/clear-text-logging-sensitive-data (CWE-312)
- Exclude py/polynomial-redos (CWE-730)
- Skip scanning tests/, docs/, and UI build output

NOTE: The Default Setup must be disabled in repo Settings > Code security
before merging, otherwise both will run simultaneously.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/codeql.yml

@@ -0,0 +1,54 @@
+name: "CodeQL"
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    # Run weekly on Sundays at 04:00 UTC
+    - cron: "0 4 * * 0"
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  analyze:
+    name: Analyze (${{ matrix.language }})
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    permissions:
+      security-events: write
+      packages: read
+      actions: read
+      contents: read
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - language: actions
+            build-mode: none
+          - language: javascript-typescript
+            build-mode: none
+          - language: python
+            build-mode: none
+          - language: ruby
+            build-mode: none
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: ${{ matrix.language }}
+          build-mode: ${{ matrix.build-mode }}
+          config-file: ./.github/codeql/codeql-config.yml
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v3
+        with:
+          category: "/language:${{ matrix.language }}"