fix: start system default sync channels by default

Create and restart paths enable IsSystemDefault channels; SyncPage auto-starts after save.

Co-authored-by: Cursor <cursoragent@cursor.com>

platform/internal/dbsync/manager.go

@@ -28,7 +28,8 @@ func (m *Manager) StartAll(ctx context.Context) {
 		return
 	}
 	for _, ch := range list {
-		if ch.Enabled {
+		// 公司默认同步通道默认运行中（即使历史记录曾为 Enabled=false）
+		if ch.Enabled || ch.IsSystemDefault {
 			_ = m.StartChannel(ch.ID)
 		}
 	}