feat(apk): 增加公开APK管理接口和CI/CD工作流

- 新增获取最新APK版本信息和下载APK的公开接口
- 更新README文档，添加APK管理接口的使用说明
- 实现CI/CD工作流，支持自动构建和部署
- 优化APK存储逻辑，确保只保留最新APK文件

.gitea/workflows/build.yml

@@ -0,0 +1,95 @@
+name: Build Updates Server
+
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+    branches:
+      - master
+      - main
+
+env:
+  GO_VERSION: '1.25'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ env.GO_VERSION }}
+          cache: true
+
+      - name: Go cache info
+        run: |
+          echo "Go cache directory:"
+          go env GOCACHE
+          echo "Go module cache directory:"
+          go env GOMODCACHE
+
+      - name: Download dependencies
+        run: go mod download
+
+      - name: Build
+        env:
+          GOOS: linux
+          GOARCH: amd64
+          CGO_ENABLED: 0
+        run: go build -v -ldflags="-s -w" -o server ./cmd/server
+
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v3
+        with:
+          name: updates-server-linux-amd64
+          path: server
+
+  build-docker:
+    runs-on: ubuntu-latest
+    needs: build
+    if: github.event_name == 'push'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to Gitea Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: code.littlelan.cn
+          username: ${{ secrets.GIT_USERNAME }}
+          password: ${{ secrets.GIT_TOKEN }}
+
+      - name: Download artifact
+        uses: actions/download-artifact@v3
+        with:
+          name: updates-server-linux-amd64
+
+      - name: Ensure binary executable
+        run: chmod +x ./server
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          push: true
+          tags: |
+            code.littlelan.cn/carrot_bbs/updates-server:latest
+            code.littlelan.cn/carrot_bbs/updates-server:${{ github.sha }}
+          platforms: linux/amd64
+          cache-from: type=registry,ref=code.littlelan.cn/carrot_bbs/updates-server:buildcache
+          cache-to: type=registry,ref=code.littlelan.cn/carrot_bbs/updates-server:buildcache,mode=max
+
+      - name: Summary
+        run: |
+          echo "## Build Summary" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "**Image:** code.littlelan.cn/carrot_bbs/updates-server" >> $GITHUB_STEP_SUMMARY
+          echo "**Tags:** latest, ${{ github.sha }}" >> $GITHUB_STEP_SUMMARY