fix(web): use 127.0.0.1 instead of localhost in Vite proxy

Fixes ECONNREFUSED ::1:3000 on Windows where localhost resolves to IPv6
but Fastify binds to IPv4 (0.0.0.0).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/vite.config.ts

@@ -6,9 +6,9 @@ export default defineConfig({
   server: {
     port: 5173,
     proxy: {
-      '/api': 'http://localhost:3000',
+      '/api': 'http://127.0.0.1:3000',
       '/socket.io': {
-        target: 'http://localhost:3000',
+        target: 'http://127.0.0.1:3000',
         ws: true,
       },
     },