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/service/gemini_token_refresher.go

@@ -1,45 +1,45 @@
-package service
-
-import (
-	"context"
-	"time"
-)
-
-type GeminiTokenRefresher struct {
-	geminiOAuthService *GeminiOAuthService
-}
-
-func NewGeminiTokenRefresher(geminiOAuthService *GeminiOAuthService) *GeminiTokenRefresher {
-	return &GeminiTokenRefresher{geminiOAuthService: geminiOAuthService}
-}
-
-func (r *GeminiTokenRefresher) CanRefresh(account *Account) bool {
-	return account.Platform == PlatformGemini && account.Type == AccountTypeOAuth
-}
-
-func (r *GeminiTokenRefresher) NeedsRefresh(account *Account, refreshWindow time.Duration) bool {
-	if !r.CanRefresh(account) {
-		return false
-	}
-	expiresAt := account.GetCredentialAsTime("expires_at")
-	if expiresAt == nil {
-		return false
-	}
-	return time.Until(*expiresAt) < refreshWindow
-}
-
-func (r *GeminiTokenRefresher) Refresh(ctx context.Context, account *Account) (map[string]any, error) {
-	tokenInfo, err := r.geminiOAuthService.RefreshAccountToken(ctx, account)
-	if err != nil {
-		return nil, err
-	}
-
-	newCredentials := r.geminiOAuthService.BuildAccountCredentials(tokenInfo)
-	for k, v := range account.Credentials {
-		if _, exists := newCredentials[k]; !exists {
-			newCredentials[k] = v
-		}
-	}
-
-	return newCredentials, nil
-}
+package service
+
+import (
+	"context"
+	"time"
+)
+
+type GeminiTokenRefresher struct {
+	geminiOAuthService *GeminiOAuthService
+}
+
+func NewGeminiTokenRefresher(geminiOAuthService *GeminiOAuthService) *GeminiTokenRefresher {
+	return &GeminiTokenRefresher{geminiOAuthService: geminiOAuthService}
+}
+
+func (r *GeminiTokenRefresher) CanRefresh(account *Account) bool {
+	return account.Platform == PlatformGemini && account.Type == AccountTypeOAuth
+}
+
+func (r *GeminiTokenRefresher) NeedsRefresh(account *Account, refreshWindow time.Duration) bool {
+	if !r.CanRefresh(account) {
+		return false
+	}
+	expiresAt := account.GetCredentialAsTime("expires_at")
+	if expiresAt == nil {
+		return false
+	}
+	return time.Until(*expiresAt) < refreshWindow
+}
+
+func (r *GeminiTokenRefresher) Refresh(ctx context.Context, account *Account) (map[string]any, error) {
+	tokenInfo, err := r.geminiOAuthService.RefreshAccountToken(ctx, account)
+	if err != nil {
+		return nil, err
+	}
+
+	newCredentials := r.geminiOAuthService.BuildAccountCredentials(tokenInfo)
+	for k, v := range account.Credentials {
+		if _, exists := newCredentials[k]; !exists {
+			newCredentials[k] = v
+		}
+	}
+
+	return newCredentials, nil
+}