Refine knowledge brain workflow

Align the brain prompts, graph view, and startup defaults with the
latest phase 1 flow so local runs and navigation stay consistent.

frontend/vite.config.ts

@@ -1,8 +1,11 @@
-import { defineConfig } from 'vite'
+import { defineConfig, loadEnv } from 'vite'
 import vue from '@vitejs/plugin-vue'
 import path from 'path'
 
-export default defineConfig({
+export default defineConfig(({ mode }) => {
+  const env = loadEnv(mode, __dirname, '')
+
+  return {
   plugins: [vue()],
   resolve: {
     alias: {
@@ -12,9 +15,10 @@ export default defineConfig({
   server: {
     proxy: {
       '/api': {
-        target: 'http://localhost:9527',
+        target: env.VITE_API_URL,
         changeOrigin: true,
       },
     },
   },
+}
 })