perf(ci): 后端镜像构建优化——腾讯云Maven镜像源+BuildKit缓存

- 镜像源从阿里云换成腾讯云（内网直连，解决依赖下载仅几十KB/s的问题）
- RUN 加 BuildKit cache mount 持久化 /root/.m2/repository，跨构建复用
- CI 构建步骤显式启用 DOCKER_BUILDKIT=1

.gitea/workflows/deploy.yml

@@ -47,6 +47,7 @@ jobs:
       - name: 构建后端镜像
         run: |
           set -euo pipefail
+          export DOCKER_BUILDKIT=1
           docker build -t freedom-admin:latest /opt/freedom/workspace-admin
 
       - name: 部署后端服务

Dockerfile

@@ -6,7 +6,7 @@
 FROM maven:3.6.3-jdk-8 AS builder
 WORKDIR /build
 
-# 配置 Maven 国内镜像源，加速依赖下载
+# 配置腾讯云镜像源（腾讯云服务器内网直连，速度远快于公网阿里云）
 RUN mkdir -p /root/.m2 && \
     echo '<?xml version="1.0" encoding="UTF-8"?>' > /root/.m2/settings.xml && \
     echo '<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"' >> /root/.m2/settings.xml && \
@@ -14,10 +14,10 @@ RUN mkdir -p /root/.m2 && \
     echo '  xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">' >> /root/.m2/settings.xml && \
     echo '  <mirrors>' >> /root/.m2/settings.xml && \
     echo '    <mirror>' >> /root/.m2/settings.xml && \
-    echo '      <id>aliyun</id>' >> /root/.m2/settings.xml && \
+    echo '      <id>tencent</id>' >> /root/.m2/settings.xml && \
     echo '      <mirrorOf>central</mirrorOf>' >> /root/.m2/settings.xml && \
-    echo '      <name>Aliyun Maven</name>' >> /root/.m2/settings.xml && \
-    echo '      <url>https://maven.aliyun.com/repository/central</url>' >> /root/.m2/settings.xml && \
+    echo '      <name>Tencent Cloud Maven</name>' >> /root/.m2/settings.xml && \
+    echo '      <url>https://mirrors.cloud.tencent.com/nexus/repository/maven-public/</url>' >> /root/.m2/settings.xml && \
     echo '    </mirror>' >> /root/.m2/settings.xml && \
     echo '  </mirrors>' >> /root/.m2/settings.xml && \
     echo '</settings>' >> /root/.m2/settings.xml
@@ -26,8 +26,8 @@ RUN mkdir -p /root/.m2 && \
 COPY pom.xml .
 COPY src ./src
 
-# 打包（跳过测试），产物 target/freedom-admin-1.0.1.jar
-RUN mvn -B clean package -DskipTests
+# 打包（跳过测试），使用 BuildKit cache mount 持久化 Maven 仓库，跨构建复用
+RUN --mount=type=cache,target=/root/.m2/repository mvn -B clean package -DskipTests
 
 # ---------- 运行阶段 ----------
 FROM openjdk:8-jre-slim