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/sysutil/restart.go

@@ -1,47 +1,47 @@
-package sysutil
-
-import (
-	"log"
-	"os"
-	"runtime"
-	"time"
-)
-
-// RestartService triggers a service restart by gracefully exiting.
-//
-// This relies on systemd's Restart=always configuration to automatically
-// restart the service after it exits. This is the industry-standard approach:
-//   - Simple and reliable
-//   - No sudo permissions needed
-//   - No complex process management
-//   - Leverages systemd's native restart capability
-//
-// Prerequisites:
-//   - Linux OS with systemd
-//   - Service configured with Restart=always in systemd unit file
-func RestartService() error {
-	if runtime.GOOS != "linux" {
-		log.Println("Service restart via exit only works on Linux with systemd")
-		return nil
-	}
-
-	log.Println("Initiating service restart by graceful exit...")
-	log.Println("systemd will automatically restart the service (Restart=always)")
-
-	// Give a moment for logs to flush and response to be sent
-	go func() {
-		time.Sleep(100 * time.Millisecond)
-		os.Exit(0)
-	}()
-
-	return nil
-}
-
-// RestartServiceAsync is a fire-and-forget version of RestartService.
-// It logs errors instead of returning them, suitable for goroutine usage.
-func RestartServiceAsync() {
-	if err := RestartService(); err != nil {
-		log.Printf("Service restart failed: %v", err)
-		log.Println("Please restart the service manually: sudo systemctl restart sub2api")
-	}
-}
+package sysutil
+
+import (
+	"log"
+	"os"
+	"runtime"
+	"time"
+)
+
+// RestartService triggers a service restart by gracefully exiting.
+//
+// This relies on systemd's Restart=always configuration to automatically
+// restart the service after it exits. This is the industry-standard approach:
+//   - Simple and reliable
+//   - No sudo permissions needed
+//   - No complex process management
+//   - Leverages systemd's native restart capability
+//
+// Prerequisites:
+//   - Linux OS with systemd
+//   - Service configured with Restart=always in systemd unit file
+func RestartService() error {
+	if runtime.GOOS != "linux" {
+		log.Println("Service restart via exit only works on Linux with systemd")
+		return nil
+	}
+
+	log.Println("Initiating service restart by graceful exit...")
+	log.Println("systemd will automatically restart the service (Restart=always)")
+
+	// Give a moment for logs to flush and response to be sent
+	go func() {
+		time.Sleep(100 * time.Millisecond)
+		os.Exit(0)
+	}()
+
+	return nil
+}
+
+// RestartServiceAsync is a fire-and-forget version of RestartService.
+// It logs errors instead of returning them, suitable for goroutine usage.
+func RestartServiceAsync() {
+	if err := RestartService(); err != nil {
+		log.Printf("Service restart failed: %v", err)
+		log.Println("Please restart the service manually: sudo systemctl restart sub2api")
+	}
+}