ci: add dedicated PR verification workflow

Author: magnusp

.github/workflows/ci.yml

@@ -1,10 +1,8 @@
-name: CI & Integration Tests
+name: CI
 
 on:
   push:
     branches: [ "main" ]
-  pull_request:
-    branches: [ "main" ]
 
 permissions:
   contents: read

.github/workflows/pr.yml

@@ -0,0 +1,34 @@
+name: PR Verification
+
+on:
+  pull_request:
+    branches: [ "main" ]
+    types: [opened, synchronize, reopened]
+
+permissions:
+  contents: read
+
+jobs:
+  verify:
+    name: Build & Test (Java ${{ matrix.java-version }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        java-version: ['25', '26']
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Amazon Corretto ${{ matrix.java-version }}
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'corretto'
+          java-version: ${{ matrix.java-version }}
+          cache: 'maven'
+
+      - name: Check Code Formatting (Spotless)
+        run: mvn --batch-mode spotless:check
+
+      - name: Run Tests and Verifications
+        run: mvn --batch-mode clean verify