fix: 简化 Dockerfile，Drone CI 已构建 jar 包

Dockerfile

@@ -1,18 +1,8 @@
-FROM ccr.ccs.tencentyun.com/violin/eclipse-temurin:22-jdk AS builder
-
-WORKDIR /app
-
-COPY pom.xml .
-COPY src ./src
-
-RUN apk add --no-cache maven && \
-    mvn clean package -DskipTests
-
 FROM ccr.ccs.tencentyun.com/violin/eclipse-temurin:22-jre
 
 WORKDIR /app
 
-COPY --from=builder /app/target/*.jar app.jar
+COPY target/*.jar app.jar
 
 EXPOSE 8080