Add GitHub Actions workflow for build and release

Introduces a workflow that builds a shaded JAR on pushes to main, computes a version based on the current UTC date and time, and creates a GitHub release with the generated artifact.

Author: CoasterFreakDE

.github/workflows/release.yml

@@ -0,0 +1,62 @@
+name: Build & Release
+
+on:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: write
+
+jobs:
+  build-and-release:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: "25"
+          cache: gradle
+
+      - name: Compute version/tag
+        id: ver
+        shell: bash
+        run: |
+          VERSION="$(date -u +%Y.%m.%d.%H%M)"
+          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
+          echo "tag=v$VERSION" >> "$GITHUB_OUTPUT"
+
+      - name: Build (shaded jar)
+        shell: bash
+        env:
+          VERSION_OVERRIDE: ${{ steps.ver.outputs.version }}
+        run: |
+          chmod +x ./gradlew
+          ./gradlew build -x test
+
+      - name: Locate shaded jar
+        id: jar
+        shell: bash
+        run: |
+          JAR="$(ls -1 build/libs/*-shaded.jar | head -n 1)"
+          if [ -z "$JAR" ]; then
+            echo "No shaded jar found in build/libs"
+            ls -la build/libs || true
+            exit 1
+          fi
+          echo "path=$JAR" >> "$GITHUB_OUTPUT"
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: ${{ steps.ver.outputs.tag }}
+          name: Release ${{ steps.ver.outputs.tag }}
+          generate_release_notes: true
+          files: |
+            ${{ steps.jar.outputs.path }}
+