Set up project scaffolding: GitHub Actions workflows, issue templates, changelog, contributing guidelines, MIT license, and README

.github/workflows/codeql.yml

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+# CodeQL: static security analysis (free for public repos).
+name: CodeQL
+
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+    branches: [ main, master ]
+  schedule:
+    - cron: '0 6 * * 1'
+
+jobs:
+  analyze:
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+      actions: read
+      contents: read
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: java
+
+      - name: Build (for CodeQL)
+        run: |
+          chmod +x gradlew
+          ./gradlew compileJava --no-daemon
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v3

.github/workflows/dependency-review.yml

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+# On PRs: checks dependency changes for known vulnerabilities.
+# Useful when Dependabot or manual dependency updates are used in PRs.
+
+name: Dependency Review
+
+on:
+  pull_request:
+    branches: [main, master]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  review:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Dependency Review
+        uses: actions/dependency-review-action@v4

.github/workflows/release.yml

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+# On push of a version tag (e.g. v1.0.0): build, create GitHub Release, upload JARs.
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 21
+          cache: gradle
+
+      - run: chmod +x gradlew && ./gradlew build --no-daemon
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v2
+        with:
+          generate_release_notes: true
+          files: build/libs/*.jar
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}