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/AdminPinnedMessageCreate.tsx

@@ -8,60 +8,7 @@ import {
   PinnedMessageUpdateRequest,
 } from '../api/adminPinnedMessages';
 import { AdminBackButton, Toggle } from '../components/admin';
-
-// Icons
-const PinIcon = () => (
-  <svg className="h-6 w-6" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={1.5}>
-    <path
-      strokeLinecap="round"
-      strokeLinejoin="round"
-      d="M19.5 10.5c0 7.142-7.5 11.25-7.5 11.25S4.5 17.642 4.5 10.5a7.5 7.5 0 1115 0z"
-    />
-    <path strokeLinecap="round" strokeLinejoin="round" d="M15 10.5a3 3 0 11-6 0 3 3 0 016 0z" />
-  </svg>
-);
-
-const XIcon = () => (
-  <svg className="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
-    <path strokeLinecap="round" strokeLinejoin="round" d="M6 18L18 6M6 6l12 12" />
-  </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>
-);
-
-const PhotoIcon = () => (
-  <svg className="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
-    <path
-      strokeLinecap="round"
-      strokeLinejoin="round"
-      d="M2.25 15.75l5.159-5.159a2.25 2.25 0 013.182 0l5.159 5.159m-1.5-1.5l1.409-1.409a2.25 2.25 0 013.182 0l2.909 2.909m-18 3.75h16.5a1.5 1.5 0 001.5-1.5V6a1.5 1.5 0 00-1.5-1.5H3.75A1.5 1.5 0 002.25 6v12a1.5 1.5 0 001.5 1.5zm10.5-11.25h.008v.008h-.008V8.25zm.375 0a.375.375 0 11-.75 0 .375.375 0 01.75 0z"
-    />
-  </svg>
-);
-
-const VideoIcon = () => (
-  <svg className="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
-    <path
-      strokeLinecap="round"
-      strokeLinejoin="round"
-      d="M15.75 10.5l4.72-4.72a.75.75 0 011.28.53v11.38a.75.75 0 01-1.28.53l-4.72-4.72M4.5 18.75h9a2.25 2.25 0 002.25-2.25v-9a2.25 2.25 0 00-2.25-2.25h-9A2.25 2.25 0 002.25 7.5v9a2.25 2.25 0 002.25 2.25z"
-    />
-  </svg>
-);
-
-const SaveIcon = () => (
-  <svg className="h-5 w-5" 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>
-);
+import { PinIcon, XIcon, RefreshIcon, PhotoIcon, VideoIcon, SaveIcon } from '@/components/icons';
 
 export default function AdminPinnedMessageCreate() {
   const { t } = useTranslation();
@@ -231,7 +178,7 @@ export default function AdminPinnedMessageCreate() {
         <AdminBackButton to="/admin/pinned-messages" />
         <div className="flex items-center gap-3">
           <div className="rounded-lg bg-error-500/20 p-2 text-error-400">
-            <PinIcon />
+            <PinIcon className="h-6 w-6" />
           </div>
           <div>
             <h1 className="text-xl font-bold text-dark-100">
@@ -290,7 +237,7 @@ export default function AdminPinnedMessageCreate() {
                   className="rounded-lg p-2 text-dark-400 hover:bg-dark-700 hover:text-error-400"
                   disabled={isUploading}
                 >
-                  <XIcon />
+                  <XIcon className="h-5 w-5" />
                 </button>
               </div>
               {mediaPreview && (