fix(deps): update nextjs monorepo to v15

Author: renovate[bot]

apps/next/package.json

@@ -12,7 +12,7 @@
   "dependencies": {
     "@tamagui/next-theme": "latest",
     "app": "*",
-    "next": "13.5.11",
+    "next": "15.5.4",
     "raf": "3.4.1",
     "react": "18.3.1",
     "react-dom": "18.3.1",
@@ -24,6 +24,6 @@
   "devDependencies": {
     "@tamagui/next-plugin": "latest",
     "@types/node": "18.19.124",
-    "eslint-config-next": "13.5.11"
+    "eslint-config-next": "15.5.4"
   }
 }