feat: integrate real backend API with centralized API client

- Add centralized apiPost() client (src/services/api.ts) that handles
  auth injection, error handling, and token expiry uniformly
- Implement real authentication against /accounts/api/login/ and /logout/
- Rewrite partnerApi and userAppApi to use centralized client
- Connect Partners page to /partner/list/ and /partner/create/ APIs
- Add Vite proxy rules for /accounts/api and /partner endpoints
- Update AuthUser type to match full backend user response
- Move NuqsAdapter inside BrowserRouter for correct routing context

Made-with: Cursor

vite.config.ts

@@ -12,12 +12,20 @@ export default defineConfig(({ mode }) => ({
       overlay: false,
     },
     proxy: {
-      // Proxy API requests to bypass CORS during development
+      '/accounts/api': {
+        target: 'http://0.0.0.0:8000',
+        changeOrigin: true,
+        secure: false,
+      },
+      '/partner': {
+        target: 'http://0.0.0.0:8000',
+        changeOrigin: true,
+        secure: false,
+      },
       '/api': {
         target: 'https://uat.eventifyplus.com',
         changeOrigin: true,
         secure: false,
-        rewrite: (path) => path,
       },
     },
   },