ci: 移除 GitHub actions 依赖，内网手动 clone + 系统 dotnet

内网无法访问 github.com，actions/checkout@v4 拉取失败导致 job 卡死。
改为与既有 build.yml 一致的手动 clone 本仓库方式，dotnet 用 runner 镜像预装。

.gitea/workflows/ci.yml

@@ -8,12 +8,17 @@ jobs:
   build-test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      # 内网无 GitHub，不能用 actions/checkout@v4；手动 clone 本仓库（Gitea Actions 已注入 GITHUB_TOKEN）
+      - name: 拉取源码（内网手动 clone）
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          git clone --depth 1 --branch "$GITHUB_REF_NAME" "http://x-access-token:${GITHUB_TOKEN}@gitea.yunhaixingtong.com/${{ github.repository }}.git" /tmp/src
+          cp -a /tmp/src/. .
+          rm -rf /tmp/src
 
-      - name: Setup .NET 8
+      - name: 确认 dotnet SDK
-        uses: actions/setup-dotnet@v4
+        run: dotnet --version
-        with:
-          dotnet-version: 8.0.x
 
       - name: Restore
         run: dotnet restore BasePlatformDotnet/yh-platform-net.sln
@@ -33,12 +38,16 @@ jobs:
     needs: build-test
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - name: 拉取源码（无内网 GitHub）
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          git clone --depth 1 --branch "$GITHUB_REF_NAME" "http://x-access-token:${GITHUB_TOKEN}@gitea.yunhaixingtong.com/${{ github.repository }}.git" /tmp/src
+          cp -a /tmp/src/. .
+          rm -rf /tmp/src
 
-      - name: Setup .NET 8
+      - name: 确认 dotnet SDK
-        uses: actions/setup-dotnet@v4
+        run: dotnet --version
-        with:
-          dotnet-version: 8.0.x
 
       - name: Pack
         run: dotnet pack BasePlatformDotnet/yh-platform-net.sln -c Release -o BasePlatformDotnet/artifacts
@@ -63,4 +72,4 @@ jobs:
             </packageSourceCredentials>
           </configuration>
           EOF
-          dotnet nuget push "BasePlatformDotnet/artifacts/*.nupkg" --source nexus-nuget --configfile nuget-push.config --api-key nexus
+          dotnet nuget push "BasePlatformDotnet/artifacts/*.nupkg" --source nexus-nuget --configfile nuget-push.config --api-key nexus