chore: bump version to 2026.6.15

Author: liuzhq1986

package.json

@@ -6,7 +6,7 @@
     "email": "lobsterai.project@rd.netease.com"
   },
   "license": "MIT",
-  "version": "2026.6.12",
+  "version": "2026.6.15",
   "openclaw": {
     "version": "v2026.4.14",
     "repo": "https://github.com/openclaw/openclaw.git",