feat: migrate form builder to shadcn/ui + Huge Icons

- Replace @wordpress/components with shadcn Input, Button, Switch, Select, Textarea, Label
- Replace @wordpress/icons with @hugeicons/core-free-icons and @hugeicons/react
- Update fieldTypes config with Huge Icons component references
- Migrate FormFieldOptions, FieldSettingsPanel, FormField, FormCanvas, FieldPalette

package.json

@@ -19,6 +19,7 @@
     "tw-animate-css": "^1.4.0"
   },
   "dependencies": {
+    "@hugeicons/core-free-icons": "^4.1.1",
     "@hugeicons/react": "^1.1.6",
     "@radix-ui/react-checkbox": "^1.3.3",
     "@radix-ui/react-dialog": "^1.1.15",