fix: version 2.18.3 -- F5 normal ya no muestra la version anterior tras actualizar

El service worker servia index.html desde su precache en cada navegacion.
Navegaciones pasan a NetworkFirst (cache solo offline), serve.json agrega
no-cache a html/sw.js e immutable a /assets, y se chequean actualizaciones
del SW cada 30 min y al volver a la pestaña.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/public/serve.json

@@ -0,0 +1,16 @@
+{
+  "headers": [
+    {
+      "source": "**/*.@(html|webmanifest)",
+      "headers": [{ "key": "Cache-Control", "value": "no-cache" }]
+    },
+    {
+      "source": "@(sw.js|registerSW.js|workbox-*.js)",
+      "headers": [{ "key": "Cache-Control", "value": "no-cache" }]
+    },
+    {
+      "source": "assets/**",
+      "headers": [{ "key": "Cache-Control", "value": "public, max-age=31536000, immutable" }]
+    }
+  ]
+}