refactor: split monolith into 3 microservices (frontend, backend, discord-gateway)

- Extract services into services/{frontend,backend,discord-gateway}
- Create packages/shared/ for shared logger, errors, utils, types
- Setup Modular MVC pattern in backend (controller→service→repository)
- Setup event-driven architecture in discord-gateway with Redis pub/sub
- Move Docker files to infra/docker/ with per-service Dockerfiles
- Update docker-compose.yml to use Traefik-only routing (no port exposes)
- Update GitHub Actions deploy workflow for multi-service matrix build
- Fix all import paths and resolve type errors across all services
- All 3 services pass tsc --noEmit clean

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/frontend/src/main.tsx

@@ -0,0 +1,30 @@
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import React from "react";
+import ReactDOM from "react-dom/client";
+import App from "./App";
+import "./styles.css";
+
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: {
+      staleTime: 30_000, // data stays fresh for 30s — no refetch within this window
+      gcTime: 5 * 60_000, // keep unused data in cache for 5 minutes
+      refetchOnWindowFocus: false, // avoid spamming the API on tab switches
+      retry: 2,
+    },
+  },
+});
+
+const root = document.getElementById("root");
+
+if (!root) {
+  throw new Error("Root element not found");
+}
+
+ReactDOM.createRoot(root).render(
+  <React.StrictMode>
+    <QueryClientProvider client={queryClient}>
+      <App />
+    </QueryClientProvider>
+  </React.StrictMode>,
+);