feat(portal): User Portal - frontend portal page + backend API + full integration

- Frontend: UserPortal.tsx with 5 tabs (Overview, API Keys, Recharge, Tenants, Analytics)
- Backend: user_portal.py with 10 endpoints (user profile, API keys, billing, tenants, analytics)
- Main.py: register portal router at /app/api/portal
- api/index.ts: fix corrupted line, add 29 missing adminAPI methods, export request function
- Billing.tsx: fix Package type missing description field
- App.tsx: add portal route
- All 7 portal API endpoints verified passing (7/7)
- API Key creation verified working
- Frontend build: 476 modules, 0 errors

frontend/src/pages/admin/Billing.tsx

@@ -2,7 +2,7 @@ import { useState, useEffect, useCallback } from 'react';
 import { adminAPI } from '@/api';
 
 interface Rule { id: string; name: string; billing_type: string; model_name: string; rate: number; free_quota: number; status: string; }
-interface Package { id: string; name: string; tokens: number; bonus_tokens: number; price: number; original_price: number; is_popular: number; status: string; }
+interface Package { id: string; name: string; description: string; tokens: number; bonus_tokens: number; price: number; original_price: number; is_popular: number; status: string; }
 interface Transaction { id: string; user_id: string; username: string; transaction_type: string; amount: number; tokens: number; status: string; created_at: string; description: string; }
 interface Stats { total_revenue: number; total_consumption: number; total_transactions: number; pending_invoices: number; active_rules: number; active_packages: number; daily_revenue_7d: { date: string; revenue: number }[]; }