Add GitHub Actions CI and GitHub Release workflow (#5)

- ci.yml: build and test on every push/PR across Java 11, 17, and 21
- release.yml: triggered by version tag push (v*.*.*) or manual dispatch;
  builds JARs and attaches them to a GitHub Release automatically

No secrets required. Maven Central publishing to be added in a follow-up
once Sonatype credentials are available.

Co-authored-by: Pratik Lala <[email protected]>

Author: pratik3558

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI — Build and Test
+
+on:
+  push:
+    branches: ["**"]
+    tags-ignore: ["v*"]
+  pull_request:
+    branches: ["**"]
+
+jobs:
+  build:
+    name: Build and Test (Java ${{ matrix.java }})
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: ['11', '17', '21']
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK ${{ matrix.java }}
+        uses: actions/setup-java@v4
+        with:
+          java-version: ${{ matrix.java }}
+          distribution: corretto
+          cache: maven
+
+      - name: Build and test
+        run: mvn --batch-mode clean verify
+
+      - name: Upload test results
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: test-results-java-${{ matrix.java }}
+          path: target/surefire-reports/
+          retention-days: 7

.github/workflows/release.yml

@@ -0,0 +1,67 @@
+name: Release — GitHub Release
+
+# Trigger: push a version tag
+#   git tag v1.0.0 && git push origin v1.0.0
+#
+# No secrets required. Builds the JARs and attaches them to a GitHub Release.
+# Maven Central publishing will be added in a future workflow once credentials are available.
+
+on:
+  push:
+    tags:
+      - "v*.*.*"
+  workflow_dispatch:
+    inputs:
+      version:
+        description: "Version to release (e.g. 1.0.0) — without the 'v' prefix"
+        required: true
+
+jobs:
+  release:
+    name: Build and Publish GitHub Release
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v4
+        with:
+          java-version: '11'
+          distribution: corretto
+          cache: maven
+
+      - name: Determine version
+        id: version
+        run: |
+          if [ -n "${{ github.event.inputs.version }}" ]; then
+            VERSION="${{ github.event.inputs.version }}"
+          else
+            VERSION="${GITHUB_REF_NAME#v}"
+          fi
+          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
+          echo "Releasing version: $VERSION"
+
+      - name: Set Maven version
+        run: |
+          mvn --batch-mode versions:set \
+            -DnewVersion=${{ steps.version.outputs.version }} \
+            -DgenerateBackupPoms=false
+
+      - name: Build and test
+        run: mvn --batch-mode clean verify
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: v${{ steps.version.outputs.version }}
+          name: v${{ steps.version.outputs.version }}
+          generate_release_notes: true
+          make_latest: true
+          files: |
+            target/json2jsontransformer-*.jar
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}