fix(web): proxy the dev API to 127.0.0.1 (uvicorn listens on IPv4 only)

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

web/vite.config.ts

@@ -8,6 +8,6 @@ export default defineConfig({
   base: "./",
   server: {
     port: 5173,
-    proxy: { "/api": { target: process.env.API_TARGET ?? "http://localhost:8000", changeOrigin: true } },
+    proxy: { "/api": { target: process.env.API_TARGET ?? "http://127.0.0.1:8000", changeOrigin: true } },
   },
 });