fix(ci): bump container memory to 8g and cap native-image xmx at 4g

Native-image was OOM-killed (exit 137) during inlining phase. The
runner has no implicit memory limit on container jobs, so native-image
probed all available memory and got killed by the host OOM killer.

Fix:
- Set container options: --memory=8g (hard cap for the build container)
- Pass -Dquarkus.native.native-image-xmx=4g to mvn (limits the
  native-image JVM heap to 4g, leaves 4g headroom for the rest
  of the toolchain: GraalVM, glibc, Maven, etc.)

.gitea/workflows/ci.yml

@@ -19,6 +19,7 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: maven:3.9.6-eclipse-temurin-21
+      options: --memory=8g
     steps:
       - name: Install git, node, gcc, and basic tools
         run: |
@@ -58,7 +59,7 @@ jobs:
           restore-keys: ${{ runner.os }}-node-
 
       - name: Build (Native)
-        run: mvn package -Pnative -B -DskipTests
+        run: mvn package -Pnative -B -DskipTests -Dquarkus.native.native-image-xmx=4g
 
       - name: Upload Native binary
         uses: actions/upload-artifact@v4