feat(devices): 设备默认名「平台简写·主机名」+ 支持重命名(1.0.13)

① 默认名:DeviceIdentity 改「平台简写(Win/Mac/Linux/iOS/Andr)·主机名」,主机名截
   到 8、总长≈12(替代裸主机名,更短)。
② 重命名:新端点 POST /v1/me/devices/{uuid}/rename(Service.RenameDevice 校验归属+
   截 64);store.UpdateName;客户端 account_api.renameDevice + provider.rename +
   「我的设备」⋯ 菜单加「重命名」+ 输入弹窗;l10n(zh/en)。
③ 版本 1.0.13。
测试:server RenameDevice(归属/空名/404)+ 客户端 rename widget;全量 go/flutter 绿。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/internal/devices/service.go

@@ -312,6 +312,36 @@ func (svc *Service) ForceLogout(ctx context.Context, userID int64, deviceUUID st
 	return nil
 }
 
+// RenameDevice sets a device's display name (ownership-checked). Empty name →
+// 400; name is trimmed + truncated to 64 runes.
+//
+//   - device not found            → 404
+//   - device owned by another user → 403
+func (svc *Service) RenameDevice(ctx context.Context, userID int64, deviceUUID, rawName string) *apierr.Error {
+	uuid := strings.TrimSpace(deviceUUID)
+	name := strings.TrimSpace(rawName)
+	if uuid == "" || name == "" {
+		return apierr.ErrBadRequest
+	}
+	if r := []rune(name); len(r) > 64 {
+		name = string(r[:64])
+	}
+	dev, err := svc.store.FindByUUID(ctx, uuid)
+	if err != nil {
+		return apierr.ErrInternal
+	}
+	if dev == nil {
+		return apierr.ErrNotFound
+	}
+	if dev.UserID != userID {
+		return apierr.ErrForbidden
+	}
+	if err := svc.store.UpdateName(ctx, dev.ID, name); err != nil {
+		return apierr.ErrInternal
+	}
+	return nil
+}
+
 // revokeDeviceSessions marks all of a device's sessions revoked and drops their
 // refresh JTIs from the Redis whitelist. Best-effort.
 func (svc *Service) revokeDeviceSessions(ctx context.Context, userID, deviceID int64) {