build(deps): typescript 5 → 6 (web + server)

TS6 más estricto con imports side-effect de CSS → añadido src/vite-env.d.ts
(/// reference vite/client) que faltaba. Verificado local: server tsc OK, web
tsc+vite build OK.

server/package-lock.json

@@ -18,7 +18,7 @@
         "drizzle-kit": "^0.31.0",
         "socket.io-client": "^4.8.1",
         "tsx": "^4.19.2",
-        "typescript": "^5.7.2",
+        "typescript": "^6.0.0",
         "vitest": "^4.0.0"
       }
     },
@@ -3888,9 +3888,9 @@
       }
     },
     "node_modules/typescript": {
-      "version": "5.9.3",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
-      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
+      "version": "6.0.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-6.0.3.tgz",
+      "integrity": "sha512-y2TvuxSZPDyQakkFRPZHKFm+KKVqIisdg9/CZwm9ftvKXLP8NRWj38/ODjNbr43SsoXqNuAisEf1GdCxqWcdBw==",
       "dev": true,
       "license": "Apache-2.0",
       "bin": {