feat(deploy): 新增 Forgejo NAS 自托管 Git + CI/CD 配置

- deploy/runner/docker-compose.forgejo.yml：Forgejo + act_runner，ROOT_URL 参数化
- .gitea/workflows/ci.yml：非 main 分支测试
- .gitea/workflows/deploy.yml：main 推送自动构建、创建 Forgejo Release、部署到 EC2
- .gitea/workflows/backup.yml：每日 02:00 备份 MySQL 到 NAS /volume1/backups

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -0,0 +1,30 @@
+name: CI
+
+on:
+  push:
+    branches-ignore: [main]
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: backend/go.mod
+          cache-dependency-path: backend/go.sum
+
+      - name: Go tests
+        working-directory: backend
+        run: go test ./...
+
+      - uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+          cache: true
+
+      - name: Flutter tests
+        working-directory: client
+        run: flutter test