chore: bump version to v2.6.8

Bump frontend package version to v2.6.8 for the latest chart scope and CI behavior updates.

Author: leolionart

frontend/package.json

@@ -1,7 +1,7 @@
 {
     "name": "cliproxy-dashboard",
     "private": true,
-    "version": "2.6.7",
+    "version": "2.6.8",
     "type": "module",
     "scripts": {
         "dev": "vite",