Migrate backend from Go to Quarkus (Java 21 / JAX-RS)

- Replaced Go stdlib server with Quarkus (RESTEasy Reactive + Jackson)
- 7 Java classes: Game POJO, GameService (JSON file I/O), 4 REST resources, static file serving
- Same JSON-per-game storage, same ZIP upload + bundle creation
- Same Svelte frontend (unchanged), built into the JAR via maven-resources-plugin
- Multi-stage Dockerfile: Node → Maven → JRE runtime

Dockerfile

@@ -1,4 +1,4 @@
-# Dostalgia — Multi-stage Docker build
+# Dostalgia — Quarkus multi-stage build
 
 # ─── 1. Build frontend ───────────────────────────
 FROM node:20-bookworm AS frontend
@@ -6,22 +6,23 @@ WORKDIR /build
 COPY frontend/package.json frontend/package-lock.json ./
 RUN npm ci 2>/dev/null || npm install --legacy-peer-deps
 COPY frontend/ ./
-RUN npx vite build
+RUN npm run build
 
-# ─── 2. Build Go binary ──────────────────────────
-FROM golang:1.23-bookworm AS gobuild
+# ─── 2. Build Quarkus app ────────────────────────
+FROM maven:3-eclipse-temurin-21 AS build
 WORKDIR /build
-COPY go.mod ./
-COPY *.go ./
+COPY pom.xml ./
+COPY src ./src
+# Copy the built frontend into the source tree so maven-resources-plugin picks it up
 COPY --from=frontend /build/dist ./frontend/dist/
-RUN CGO_ENABLED=0 go build -o /dostalgia .
+RUN mvn package -DskipTests -q
 
 # ─── 3. Runtime ──────────────────────────────────
-FROM debian:bookworm-slim
-RUN apt-get update -qq && apt-get install -y -qq --no-install-recommends ca-certificates tzdata && rm -rf /var/lib/apt/lists/*
-COPY --from=gobuild /dostalgia /dostalgia
-VOLUME /data
+FROM eclipse-temurin:21-jre-alpine
+WORKDIR /app
+# Quarkus uber-jar layout
+COPY --from=build /build/target/quarkus-app/ /app/
 EXPOSE 8765
+VOLUME /data
 ENV DOSTALGIA_DATA=/data
-ENV PORT=8765
-ENTRYPOINT ["/dostalgia"]
+ENTRYPOINT ["java", "-jar", "quarkus-run.jar"]