refactor(cabinet): migrate inline SVG icons to the central react-icons set

Audit-driven sweep: replaced 168 hand-written inline <svg> icons across 77
files with the central Phosphor (react-icons/pi) components from
@/components/icons, preserving each icon's size classes and colour (dynamic
stroke colours via the parent's currentColor, RefreshIcon's spinning state,
conditional rotate-180 chevrons).

Verified: tsc + vite build + eslint clean; an adversarial diff review of all
changed files found the replacements correct (70 files clean, 0 blockers).
Remaining inline <svg> dropped from 262 to ~95 — the survivors are legitimate
non-icons (brand/provider logos, loading spinners & framer-motion animations,
charts/sparklines, background decoration) plus a few ambiguous glyphs.

src/pages/AdminApps.tsx

@@ -3,6 +3,7 @@ import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { useTranslation } from 'react-i18next';
 import { adminAppsApi } from '../api/adminApps';
 import { usePlatform } from '../platform/hooks/usePlatform';
+import { BackIcon } from '@/components/icons';
 
 export default function AdminApps() {
   const { t } = useTranslation();
@@ -45,15 +46,7 @@ export default function AdminApps() {
             onClick={() => navigate('/admin')}
             className="flex h-10 w-10 items-center justify-center rounded-xl border border-dark-700 bg-dark-800 transition-colors hover:border-dark-600"
           >
-            <svg
-              className="h-5 w-5 text-dark-400"
-              fill="none"
-              viewBox="0 0 24 24"
-              stroke="currentColor"
-              strokeWidth={2}
-            >
-              <path strokeLinecap="round" strokeLinejoin="round" d="M15.75 19.5L8.25 12l7.5-7.5" />
-            </svg>
+            <BackIcon className="h-5 w-5 text-dark-400" />
           </button>
         )}
         <h1 className="text-2xl font-bold text-dark-50 sm:text-3xl">{t('admin.apps.title')}</h1>