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/components/admin/ButtonsTab.tsx

@@ -9,6 +9,7 @@ import {
   ButtonSection,
   BOT_LOCALES,
 } from '../../api/buttonStyles';
+import { ChevronDownIcon } from '@/components/icons';
 import { Toggle } from './Toggle';
 import { useNotify } from '../../platform/hooks/useNotify';
 import { useNativeDialog } from '../../platform/hooks/useNativeDialog';
@@ -284,15 +285,9 @@ export function ButtonsTab() {
                     {t('admin.buttons.customLabels')}
                     {hasCustomLabels && <span className="h-1.5 w-1.5 rounded-full bg-accent-500" />}
                   </span>
-                  <svg
+                  <ChevronDownIcon
                     className={`h-3.5 w-3.5 transition-transform ${isExpanded ? 'rotate-180' : ''}`}
-                    fill="none"
-                    viewBox="0 0 24 24"
-                    stroke="currentColor"
-                    strokeWidth={2}
-                  >
-                    <path strokeLinecap="round" strokeLinejoin="round" d="M19 9l-7 7-7-7" />
-                  </svg>
+                  />
                 </button>
                 {isExpanded && (
                   <div className="mt-2 space-y-2">