Fix SSE route dependency and align architecture docs

frontend/vite.config.ts

@@ -1,17 +1,24 @@
-import { defineConfig } from 'vite'
+import { defineConfig, loadEnv } from 'vite'
 import react from '@vitejs/plugin-react'
 
 // https://vite.dev/config/
-export default defineConfig({
-  plugins: [react()],
-  server: {
-    host: '0.0.0.0',
-    port: 5173,
-    proxy: {
-      '^/api/.*': {
-        target: 'http://6.86.80.8:8000',
-        changeOrigin: true,
+export default defineConfig(({ mode }) => {
+  const env = loadEnv(mode, process.cwd(), '')
+  const apiHost = env.API_HOST || 'localhost'
+  const apiPort = env.API_PORT || '8000'
+  const proxyTarget = env.VITE_API_PROXY_TARGET || `http://${apiHost}:${apiPort}`
+
+  return {
+    plugins: [react()],
+    server: {
+      host: '0.0.0.0',
+      port: Number(env.FRONTEND_PORT || 5173),
+      proxy: {
+        '/api': {
+          target: proxyTarget,
+          changeOrigin: true,
+        },
       },
     },
-  },
+  }
 })