feat: 品牌重命名 Sub2API -> TianShuAPI

- 前端: 所有界面显示、i18n 文本、组件中的品牌名称
- 后端: 服务层、设置默认值、邮件模板、安装向导
- 数据库: 迁移脚本注释
- 保持功能完全一致，仅更改品牌名称

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

backend/internal/pkg/geminicli/drive_client_test.go

@@ -1,18 +1,18 @@
-package geminicli
-
-import "testing"
-
-func TestDriveStorageInfo(t *testing.T) {
-	// 测试 DriveStorageInfo 结构体
-	info := &DriveStorageInfo{
-		Limit: 100 * 1024 * 1024 * 1024, // 100GB
-		Usage: 50 * 1024 * 1024 * 1024,  // 50GB
-	}
-
-	if info.Limit != 100*1024*1024*1024 {
-		t.Errorf("Expected limit 100GB, got %d", info.Limit)
-	}
-	if info.Usage != 50*1024*1024*1024 {
-		t.Errorf("Expected usage 50GB, got %d", info.Usage)
-	}
-}
+package geminicli
+
+import "testing"
+
+func TestDriveStorageInfo(t *testing.T) {
+	// 测试 DriveStorageInfo 结构体
+	info := &DriveStorageInfo{
+		Limit: 100 * 1024 * 1024 * 1024, // 100GB
+		Usage: 50 * 1024 * 1024 * 1024,  // 50GB
+	}
+
+	if info.Limit != 100*1024*1024*1024 {
+		t.Errorf("Expected limit 100GB, got %d", info.Limit)
+	}
+	if info.Usage != 50*1024*1024*1024 {
+		t.Errorf("Expected usage 50GB, got %d", info.Usage)
+	}
+}