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)

package-lock.json

@@ -55,6 +55,7 @@
         "react": "^19.2.4",
         "react-dom": "^19.2.4",
         "react-i18next": "^16.5.4",
+        "react-icons": "^5.6.0",
         "react-router": "^7.13.0",
         "react-twemoji": "^0.7.2",
         "recharts": "^3.7.0",
@@ -6908,6 +6909,15 @@
         }
       }
     },
+    "node_modules/react-icons": {
+      "version": "5.6.0",
+      "resolved": "https://registry.npmjs.org/react-icons/-/react-icons-5.6.0.tgz",
+      "integrity": "sha512-RH93p5ki6LfOiIt0UtDyNg/cee+HLVR6cHHtW3wALfo+eOHTp8RnU2kRkI6E+H19zMIs03DyxUG/GfZMOGvmiA==",
+      "license": "MIT",
+      "peerDependencies": {
+        "react": "*"
+      }
+    },
     "node_modules/react-is": {
       "version": "19.2.4",
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-19.2.4.tgz",