chore: 新增 Flutter CI 门禁工作流（零 GitHub 依赖）

- format/analyze/test 三连，与本地门禁同一套命令
- Flutter SDK 从 flutter-io.cn 下载并缓存于 runner toolcache 卷，pub 走国内镜像
- checkout 手动克隆本 Gitea 实例，concurrency 取消旧 run

.gitea/workflows/ci.yml

@@ -0,0 +1,54 @@
+# Gitea Actions 门禁：与 docs/development/git-workflow.md 的本地门禁同一套命令。
+# 零外部 action / 零 GitHub 依赖（原因见 patbond-api 的 ci.yml 头注释）。
+# Flutter SDK 从中国镜像（flutter-io.cn）下载并缓存在 runner 的 toolcache 卷中，
+# 首跑约需下载 ~900MB，之后复用缓存秒级就绪。
+# 前提：runner config.yaml 的 container.options 挂载了 toolcache 卷：
+#   options: "-v /var/run/docker.sock:/var/run/docker.sock -v gitea_toolcache:/opt/hostedtoolcache"
+name: CI
+
+on:
+  push:
+    branches: [dev]
+  pull_request:
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  flutter-gates:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout (manual)
+        run: |
+          git init -q .
+          AUTH_URL=$(echo "${{ github.server_url }}" | sed "s#https://#https://oauth2:${{ github.token }}@#")
+          git remote add origin "$AUTH_URL/${{ github.repository }}.git"
+          git fetch -q --depth 1 origin "+${{ github.ref }}:refs/ci-head"
+          git checkout -q refs/ci-head
+      - name: Install Flutter (flutter-io.cn mirror, toolcache reuse)
+        run: |
+          FLUTTER_VERSION=3.44.6
+          FLUTTER_HOME=/opt/hostedtoolcache/flutter-$FLUTTER_VERSION
+          if [ ! -x "$FLUTTER_HOME/bin/flutter" ]; then
+            echo "Downloading Flutter $FLUTTER_VERSION from flutter-io.cn ..."
+            curl -fsSL -o /tmp/flutter.tar.xz \
+              "https://storage.flutter-io.cn/flutter_infra_release/releases/stable/linux/flutter_linux_${FLUTTER_VERSION}-stable.tar.xz"
+            mkdir -p /opt/hostedtoolcache
+            tar -xf /tmp/flutter.tar.xz -C /tmp
+            mv /tmp/flutter "$FLUTTER_HOME"
+          else
+            echo "Reusing cached Flutter at $FLUTTER_HOME"
+          fi
+          git config --global --add safe.directory "$FLUTTER_HOME"
+          echo "$FLUTTER_HOME/bin" >> "$GITHUB_PATH"
+          echo "PUB_HOSTED_URL=https://pub.flutter-io.cn" >> "$GITHUB_ENV"
+          echo "FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn" >> "$GITHUB_ENV"
+      # 与本地门禁同一套命令（git-workflow.md）
+      - name: Gates
+        run: |
+          flutter --version
+          flutter pub get
+          dart format --output=none --set-exit-if-changed lib test
+          flutter analyze
+          flutter test