refactor: switch icons from react-icons to Phosphor

Replace react-icons and @radix-ui/react-icons with @phosphor-icons/react
for a consistent icon style across all dashboard panels.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -14,7 +14,7 @@
   "dependencies": {
     "@ciphera-net/ui": "^0.0.93",
     "@ducanh2912/next-pwa": "^10.2.9",
-    "@radix-ui/react-icons": "^1.3.0",
+    "@phosphor-icons/react": "^2.1.10",
     "@simplewebauthn/browser": "^13.2.2",
     "@stripe/react-stripe-js": "^5.6.0",
     "@stripe/stripe-js": "^8.7.0",
@@ -30,7 +30,6 @@
     "next": "^16.1.1",
     "react": "^19.2.3",
     "react-dom": "^19.2.3",
-    "react-icons": "^5.5.0",
     "react-markdown": "^10.1.0",
     "react-simple-maps": "^3.0.0",
     "recharts": "^2.15.0",