ci: run CodeQL checks on fork pull requests

.github/workflows/codeql.yml

@@ -0,0 +1,47 @@
+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  # Required checks must report on every PR, including forks and docs-only PRs.
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: '23 3 * * 1'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: codeql-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  analyze:
+    # These names match the existing main ruleset.
+    name: Analyze (${{ matrix.language }})
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    permissions:
+      contents: read
+      security-events: write
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [actions, c-cpp, rust, javascript-typescript]
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
+        with:
+          persist-credentials: false
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@f3c49fd1ef3281abc41069b3dd22807a60c963f6 # v4
+        with:
+          languages: ${{ matrix.language }}
+          # Match Default setup without running contributor-controlled builds.
+          build-mode: none
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@f3c49fd1ef3281abc41069b3dd22807a60c963f6 # v4
+        with:
+          category: /language:${{ matrix.language }}