Strengthen repository security

.github/workflows/codeql.yml

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+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: '27 3 * * 1'
+
+permissions:
+  contents: read
+  security-events: write
+  actions: read
+
+jobs:
+  analyze:
+    name: Analyze (${{ matrix.language }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [javascript-typescript]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: ${{ matrix.language }}
+
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@v3
+
+      - name: Perform CodeQL analysis
+        uses: github/codeql-action/analyze@v3
+        with:
+          category: /language:${{ matrix.language }}

.github/workflows/dependency-review.yml

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+name: Dependency Review
+
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  dependency-review:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Dependency review
+        uses: actions/dependency-review-action@v4

SECURITY.md

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+# Security Policy
+
+## Reporting a Vulnerability
+
+Please report suspected vulnerabilities privately through this repository's private vulnerability-reporting feature. Do not open a public issue for a potential security problem.
+
+Include enough detail to reproduce the issue safely, such as the affected version, impact, steps to reproduce, and any proof of concept.
+
+## Scope
+
+Reports about vulnerabilities in the application, its build and release process, dependencies, and repository automation are in scope.
+
+## Response
+
+Reports are reviewed as time permits. Acknowledgment and remediation timelines depend on severity, reproducibility, and available maintainer capacity.