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/proxy.go

@@ -1,35 +1,35 @@
-package service
-
-import (
-	"fmt"
-	"time"
-)
-
-type Proxy struct {
-	ID        int64
-	Name      string
-	Protocol  string
-	Host      string
-	Port      int
-	Username  string
-	Password  string
-	Status    string
-	CreatedAt time.Time
-	UpdatedAt time.Time
-}
-
-func (p *Proxy) IsActive() bool {
-	return p.Status == StatusActive
-}
-
-func (p *Proxy) URL() string {
-	if p.Username != "" && p.Password != "" {
-		return fmt.Sprintf("%s://%s:%s@%s:%d", p.Protocol, p.Username, p.Password, p.Host, p.Port)
-	}
-	return fmt.Sprintf("%s://%s:%d", p.Protocol, p.Host, p.Port)
-}
-
-type ProxyWithAccountCount struct {
-	Proxy
-	AccountCount int64
-}
+package service
+
+import (
+	"fmt"
+	"time"
+)
+
+type Proxy struct {
+	ID        int64
+	Name      string
+	Protocol  string
+	Host      string
+	Port      int
+	Username  string
+	Password  string
+	Status    string
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+func (p *Proxy) IsActive() bool {
+	return p.Status == StatusActive
+}
+
+func (p *Proxy) URL() string {
+	if p.Username != "" && p.Password != "" {
+		return fmt.Sprintf("%s://%s:%s@%s:%d", p.Protocol, p.Username, p.Password, p.Host, p.Port)
+	}
+	return fmt.Sprintf("%s://%s:%d", p.Protocol, p.Host, p.Port)
+}
+
+type ProxyWithAccountCount struct {
+	Proxy
+	AccountCount int64
+}