Upgrade Nuxt version and update configuration

- Updated Nuxt from version 3.21.1 to 4.3.1 in package.json for improved features and performance.
- Removed outdated TypeScript error suppression in nuxt.config.ts for cleaner code.
- Updated README.md to reflect the transition to Nuxt 4 and added instructions for post-upgrade steps.
- Modified error handling in middleware to use consistent error property names.

frontend-nuxt/README.md

@@ -1,6 +1,6 @@
-# HnH Map – Nuxt 3 frontend
+# HnH Map – Nuxt 4 frontend
 
-Nuxt 3 + Tailwind + DaisyUI frontend for the HnH map. Served by the Go backend under `/map/`.
+Nuxt 4 + Tailwind + DaisyUI frontend for the HnH map. Served by the Go backend under `/map/`.
 
 In dev mode the app is available at the path with baseURL **`/map/`** (e.g. `http://localhost:3000/map/`). The Go backend must be reachable (directly or via the dev proxy in `nuxt.config.ts`).
 
@@ -25,6 +25,8 @@ In dev mode the app is available at the path with baseURL **`/map/`** (e.g. `htt
 npm install
 ```
 
+After upgrading the repo (e.g. to Nuxt 4), run `npm install` in this directory, then `npx nuxt prepare`, and verify with `npm run build` and `npm run test`.
+
 ## Development
 
 ```bash

frontend-nuxt/nuxt.config.ts

@@ -39,7 +39,6 @@ export default defineNuxtConfig({
   },
 
   // Dev: proxy /map API, SSE and grids to Go backend (e.g. docker compose -f docker-compose.dev.yml)
-  // @ts-expect-error nitro types lag behind Nuxt compat v4
   nitro: {
     devProxy: {
       '/map/api': { target: 'http://backend:3080/map/api', changeOrigin: true },

frontend-nuxt/package.json

@@ -20,7 +20,7 @@
   "dependencies": {
     "leaflet": "^1.9.4",
     "md5": "^2.3.0",
-    "nuxt": "^3.21.1",
+    "nuxt": "^4.3.1",
     "vue": "^3.5.13",
     "vue-router": "^4.5.0"
   },

frontend-nuxt/server/middleware/0.uri-guard.ts

@@ -7,6 +7,6 @@ export default defineEventHandler((event) => {
   try {
     decodeURI(path)
   } catch {
-    throw createError({ statusCode: 400, statusMessage: 'Bad Request' })
+    throw createError({ status: 400, statusText: 'Bad Request' })
   }
 })