chore: Add Go proxy setup to build workflow

- Configured Go proxy settings for improved dependency management.
- Disabled Go checksum database for local development environments.

.gitea/workflows/build.yml

@@ -23,6 +23,12 @@ jobs:
           go-version: '1.25'
           cache: true
 
+      - name: Set up Go Proxy
+        run: |
+          echo "GOPROXY=https://goproxy.cn,direct" >> $GITHUB_ENV
+          echo "GOSUMDB=off" >> $GITHUB_ENV
+          echo "已设置国内 Go 代理"
+
       - name: Download dependencies
         run: go mod download