feat: Add IconCreditCard and IconCurrencyDollar to BillingManager and App components for improved icon representation

frontend/src/App.jsx

@@ -18,7 +18,8 @@ import {
   IconAlertCircle,
   IconServer,
   IconFilter,
-  IconDownload
+  IconDownload,
+  IconCreditCard
 } from '@tabler/icons-react';
 import DataManager from './DataManager';
 import ServerManager from './ServerManager';

frontend/src/BillingManager.jsx

@@ -2,27 +2,16 @@ import { useState, useEffect, useRef } from 'react';
 import axios from 'axios';
 import { 
   IconPlus, 
-  IconSearch, 
   IconEdit, 
   IconTrash, 
   IconCheck, 
-  IconX, 
   IconDatabase,
   IconRefresh,
-  IconDownload,
-  IconUpload,
   IconAlertTriangle,
-  IconServer,
-  IconChevronDown,
-  IconLink,
   IconCalendar,
   IconCreditCard,
-  IconDollarSign,
-  IconBuilding,
-  IconFlag,
-  IconExternalLink,
-  IconEye,
-  IconSettings
+  IconCurrencyDollar,
+  IconExternalLink
 } from '@tabler/icons-react';
 
 const API_URL = '/api';
@@ -384,7 +373,7 @@ function BillingManager() {
           <div className="card h-100">
             <div className="card-body d-flex align-items-center">
               <span className="avatar avatar-lg me-3 bg-purple-lt text-purple border-0">
-                <IconDollarSign size={32} />
+                <IconCurrencyDollar size={32} />
               </span>
               <div>
                 <div className="h3 mb-0 fw-bold">