feat(cabinet): migrate all icons to the panel's Phosphor set

Replace the cabinet's hand-written heroicons-style SVG icon components with
the Remnawave panel's own icon family — Phosphor via react-icons/pi (Duotone).
All icons now live in a single central barrel (src/components/icons:
index + extended-icons + editor-icons, 144 icons); every feature file imports
from it instead of redefining inline SVGs (~440 icon defs removed).

- Add react-icons dependency
- Desktop nav (AppShell) now uses the central Phosphor icons, removing a
  stroke-vs-duotone inconsistency the partial migration introduced
- Icons with custom props (SortIcon's direction, expandable chevrons) kept as
  thin Phosphor wrappers; the RemnawaveIcon brand logo and animated SVGs
  (checkmarks, spinners) are intentionally left as-is
- Restore the original per-call-site icon sizes wherever the centralized
  default differed (211 call sites)

src/pages/AdminCampaignCreate.tsx

@@ -13,32 +13,7 @@ import { partnerApi } from '../api/partners';
 import { AdminBackButton } from '../components/admin';
 import { createNumberInputHandler, toNumber } from '../utils/inputHelpers';
 import Twemoji from 'react-twemoji';
-// Icons
-const CampaignIcon = () => (
-  <svg className="h-6 w-6" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={1.5}>
-    <path
-      strokeLinecap="round"
-      strokeLinejoin="round"
-      d="M10.34 15.84c-.688-.06-1.386-.09-2.09-.09H7.5a4.5 4.5 0 110-9h.75c.704 0 1.402-.03 2.09-.09m0 9.18c.253.962.584 1.892.985 2.783.247.55.06 1.21-.463 1.511l-.657.38c-.551.318-1.26.117-1.527-.461a20.845 20.845 0 01-1.44-4.282m3.102.069a18.03 18.03 0 01-.59-4.59c0-1.586.205-3.124.59-4.59m0 9.18a23.848 23.848 0 018.835 2.535M10.34 6.66a23.847 23.847 0 008.835-2.535m0 0A23.74 23.74 0 0018.795 3m.38 1.125a23.91 23.91 0 011.014 5.395m-1.014 8.855c-.118.38-.245.754-.38 1.125m.38-1.125a23.91 23.91 0 001.014-5.395m0-3.46c.495.413.811 1.035.811 1.73 0 .695-.316 1.317-.811 1.73m0-3.46a24.347 24.347 0 010 3.46"
-    />
-  </svg>
-);
-
-const CheckIcon = () => (
-  <svg className="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
-    <path strokeLinecap="round" strokeLinejoin="round" d="M4.5 12.75l6 6 9-13.5" />
-  </svg>
-);
-
-const RefreshIcon = () => (
-  <svg className="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
-    <path
-      strokeLinecap="round"
-      strokeLinejoin="round"
-      d="M16.023 9.348h4.992v-.001M2.985 19.644v-4.992m0 0h4.992m-4.993 0l3.181 3.183a8.25 8.25 0 0013.803-3.7M4.031 9.865a8.25 8.25 0 0113.803-3.7l3.181 3.182m0-4.991v4.99"
-    />
-  </svg>
-);
+import { CampaignIcon, CheckIcon, RefreshIcon } from '@/components/icons';
 
 // Bonus type config
 const bonusTypeConfig: Record<
@@ -283,7 +258,7 @@ export default function AdminCampaignCreate() {
         <AdminBackButton />
         <div className="flex items-center gap-3">
           <div className="rounded-lg bg-accent-500/20 p-2 text-accent-400">
-            <CampaignIcon />
+            <CampaignIcon className="h-6 w-6" />
           </div>
           <div>
             <h1 className="text-xl font-bold text-dark-100">
@@ -556,7 +531,7 @@ export default function AdminCampaignCreate() {
           disabled={!isValid || createMutation.isPending}
           className="btn-primary flex items-center gap-2"
         >
-          {createMutation.isPending ? <RefreshIcon /> : <CampaignIcon />}
+          {createMutation.isPending ? <RefreshIcon /> : <CampaignIcon className="h-6 w-6" />}
           {t('admin.campaigns.form.save')}
         </button>
       </div>