🐛(frontend) return real 404s for missing hashed assets

Nginx was rewriting missing `/assets/*` files to `index.html`, so
requests for stale chunks got a 200 with the SPA shell served as a
JS module. That is what turned a plain 404 into the confusing:

  "TypeError: error loading dynamically imported module"

whenever a client loaded before a deployment requested an old chunk.

Stop rewriting missing `/assets/*` to `index.html`: those requests
now return a real 404 with `Cache-Control: no-store`. SPA route
fallback for non-asset paths is unchanged.

CHANGELOG.md

@@ -8,6 +8,10 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Fixed
+
+- ✨(frontend) recover from stale lazy-loaded chunks after a deploy
+
 ## [1.26.0] - 2026-08-12
 
 ### Added

docker/dinum-frontend/nginx/default.conf

@@ -74,6 +74,13 @@ server {
   location ~* ^/assets/.*\.(css|js|json|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
       expires 30d;
       add_header Cache-Control "public, max-age=2592000";
+      try_files $uri =404;
+      error_page 404 = @asset_missing;
+  }
+
+  location @asset_missing {
+      add_header Cache-Control "no-store" always;
+      return 404;
   }
 
   # Serve static files

src/frontend/default.conf

@@ -14,6 +14,13 @@ server {
   location ~* ^/assets/.*\.(css|js|json|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
       expires 30d;
       add_header Cache-Control "public, max-age=2592000";
+      try_files $uri =404;
+      error_page 404 = @asset_missing;
+  }
+
+  location @asset_missing {
+      add_header Cache-Control "no-store" always;
+      return 404;
   }
 
   # Serve static files

src/frontend/src/main.tsx

@@ -2,6 +2,26 @@ import React from 'react'
 import ReactDOM from 'react-dom/client'
 import App from './App.tsx'
 
+const CHUNK_RELOAD_KEY = 'vite-preload-error-reload-at'
+const RELOAD_COOLDOWN_MS = 30_000
+
+window.addEventListener('vite:preloadError', (event) => {
+  try {
+    const lastReloadAt = Number(sessionStorage.getItem(CHUNK_RELOAD_KEY)) || 0
+    if (Date.now() - lastReloadAt <= RELOAD_COOLDOWN_MS) {
+      // Recent reload didn't help: not a stale deploy, surface the error.
+      return
+    }
+    sessionStorage.setItem(CHUNK_RELOAD_KEY, String(Date.now()))
+  } catch {
+    // Without sessionStorage we cannot guard against a reload loop:
+    // don't auto-reload, let the error propagate.
+    return
+  }
+  event.preventDefault()
+  window.location.reload()
+})
+
 ReactDOM.createRoot(document.getElementById('root')!).render(
   <React.StrictMode>
     <App />