Ajoute le pipeline CI Gitea Actions (CP11 - demarche DevOps)

mvn clean verify (compile + tests) a chaque push/PR sur main, upload
des jars en artefact si succes.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -0,0 +1,34 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup JDK 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+          cache: maven
+
+      - name: Build and test
+        run: mvn -B clean verify
+
+      - name: Upload jars
+        if: success()
+        uses: actions/upload-artifact@v4
+        with:
+          name: votenetwork-jars
+          path: |
+            velocity/target/VoteNetwork-Velocity.jar
+            spigot/target/VoteNetwork-Spigot.jar
+          retention-days: 14