修复：解决分组用量 PR 的 CI 失败

恢复分组时区测试进入前的全局时区，避免污染高峰计费和支付租约测试。同步升级 Go 1.26.6 与 nanoid 3.3.18，清除后端和前端安全门禁。

.github/workflows/backend-ci.yml

@@ -32,7 +32,7 @@ jobs:
           cache-dependency-path: backend/go.sum
       - name: Verify Go version
         run: |
-          go version | grep -q 'go1.26.5'
+          go version | grep -q 'go1.26.6'
       - name: Unit tests
         working-directory: backend
         run: make test-unit
@@ -72,7 +72,7 @@ jobs:
           cache-dependency-path: backend/go.sum
       - name: Verify Go version
         run: |
-          go version | grep -q 'go1.26.5'
+          go version | grep -q 'go1.26.6'
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v9
         with:

.github/workflows/release.yml

@@ -115,7 +115,7 @@ jobs:
 
       - name: Verify Go version
         run: |
-          go version | grep -q 'go1.26.5'
+          go version | grep -q 'go1.26.6'
 
       # Docker setup for GoReleaser
       - name: Set up QEMU

.github/workflows/security-scan.yml

@@ -23,7 +23,7 @@ jobs:
           cache-dependency-path: backend/go.sum
       - name: Verify Go version
         run: |
-          go version | grep -q 'go1.26.5'
+          go version | grep -q 'go1.26.6'
       - name: Run govulncheck
         working-directory: backend
         run: |