Automate Publishing to Maven Central via CI (#29)

* Adding Publish workflow

* Remove testing branch from Changesets workflow

.github/workflows/changeset.yml

@@ -1,9 +1,7 @@
 name: Changeset
 on:
   push:
-    branches:
-      - main
-      - ullrich/add-changesets
+    branches: [ "main" ]
 
 concurrency: ${{ github.workflow }}-${{ github.ref }}
 

.github/workflows/release-gradle-publish.yml

@@ -0,0 +1,57 @@
+name: Release Gradle Publish
+
+on:
+  release:
+    types: [ created ]
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up JDK 17
+      uses: actions/setup-java@v4
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+
+    - name: Setup Gradle
+      uses: gradle/actions/setup-gradle@v4
+
+    - name: Setup Keyring
+      id: keyring
+      env:
+        KEYRING_FILE: ${{ runner.temp }}/publish-keyring.gpg
+        DATA: ${{ secrets.SIGNING_KEYRING }}
+      run: |
+        echo "Creating Keyring file at $KEYRING_FILE"
+        echo $DATA | base64 -di > $KEYRING_FILE
+        echo "keyringFile=$KEYRING_FILE" >> "$GITHUB_OUTPUT"
+
+    - name: Sanity Check
+      run: |
+        ./gradlew \
+          sdk:lint sdk-compose:lint \
+          sdk:test sdk-compose:test
+
+    - name: Publish to Maven Local
+      run: |
+        ./gradlew \
+          -Psigning.keyId="${{ secrets.SIGNING_KEYID }}" \
+          -Psigning.password="${{ secrets.SIGNING_PASSWORD }}" \
+          -Psigning.secretKeyRingFile="${{ steps.keyring.outputs.keyringFile }}" \
+          sdk:publishToMavenLocal sdk-compose:publishToMavenLocal
+
+    - name: Publish to Maven
+      run: |
+        ./gradlew \
+          -Psigning.keyId="${{ secrets.SIGNING_KEYID }}" \
+          -Psigning.password="${{ secrets.SIGNING_PASSWORD }}" \
+          -Psigning.secretKeyRingFile="${{ steps.keyring.outputs.keyringFile }}" \
+          -PNEXUS_USERNAME="${{ secrets.NEXUS_USERNAME }}" \
+          -PNEXUS_PASSWORD="${{ secrets.NEXUS_PASSWORD }}" \
+          sdk:publish sdk-compose:publish