fix(deps): update nextjs monorepo to v16

src/backend/server/Dockerfile

@@ -1,9 +1,9 @@
-FROM mcr.microsoft.com/dotnet/aspnet:10.0 AS base
+FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base
 WORKDIR /app
 EXPOSE 80
 EXPOSE 443
 
-FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
+FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
 WORKDIR /src
 
 COPY *.sln .

src/backend/server/global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "10.0.100",
+    "version": "9.0.200",
     "rollForward": "latestMajor",
     "allowPrerelease": true
   }

src/client/package.json

@@ -8,11 +8,11 @@
     "lint": "next lint"
   },
   "dependencies": {
-    "@microsoft/signalr": "10.0.0",
+    "@microsoft/signalr": "8.0.7",
     "@reduxjs/toolkit": "2.6.0",
     "@tippyjs/react": "4.2.6",
     "axios": "1.8.1",
-    "next": "15.2.1",
+    "next": "16.0.7",
     "next-pwa": "5.6.0",
     "react": "19.0.0",
     "react-dom": "19.0.0",
@@ -26,7 +26,7 @@
     "autoprefixer": "10.4.20",
     "cssnano": "7.0.6",
     "eslint": "9.21.0",
-    "eslint-config-next": "15.2.1",
+    "eslint-config-next": "16.0.7",
     "postcss": "8.5.3",
     "postcss-import": "16.1.0",
     "prettier": "3.5.3",