Add Docker support with CI workflow and runtime configuration

- Added `Dockerfile` to build a Docker image for the JavadocViewerService.
- Implemented a Gitea-based CI workflow (`deploy-image.yml`) to build and push the Docker image.
- Updated `settings.local.json` to expand permissions for the service.
- Included `-DskipTests` to Maven arguments in `JavadocService.java`.

src/main/java/codes/thischwa/jvs/service/JavadocService.java

@@ -87,7 +87,8 @@ public class JavadocService {
         "--no-transfer-progress",
         "-Dlombok.delombok.skip=true",
         "-Dcheckstyle.skip=true",
-        "-Djacoco.skip=true"
+        "-Djacoco.skip=true",
+        "-DskipTests"
     );
     pb.directory(repoDir);
     pb.redirectErrorStream(true);