feat: Nova UI component library + Studio dropdown/picker polish

- Add Nova UI library: Button, TextInput, Textarea, FormField, Select,
  NovaSelect, Checkbox, Radio/RadioGroup, Toggle, DatePicker,
  DateRangePicker, Modal + barrel index.js
- Replace all native <select> in Studio with NovaSelect (StudioFilters,
  StudioToolbar, BulkActionsBar) including frosted-glass portal and
  category group headers
- Replace native checkboxes in StudioGridCard, StudioTable, UploadSidebar,
  UploadWizard, Upload/Index with custom Checkbox component
- Add nova-scrollbar CSS utility (thin 4px, semi-transparent)
- Fix portal position drift: use viewport-relative coords (no scrollY offset)
  for NovaSelect, DatePicker and DateRangePicker
- Close portals on external scroll instead of remeasuring
- Improve hover highlight visibility in NovaSelect (bg-white/[0.13])
- Move search icon to right side in NovaSelect dropdown
- Reduce Studio layout top spacing (py-6 -> pt-4 pb-8)
- Add StudioCheckbox and SquareCheckbox backward-compat shims
- Add sync.sh rsync deploy script

resources/js/components/Studio/StudioGridCard.jsx

@@ -1,6 +1,7 @@
 import React from 'react'
 import StatusBadge from '../Badges/StatusBadge'
 import RisingBadge from '../Badges/RisingBadge'
+import Checkbox from '../ui/Checkbox'
 
 function getStatus(art) {
   if (art.deleted_at) return 'archived'
@@ -27,14 +28,13 @@ export default function StudioGridCard({ artwork, selected, onSelect, onAction }
       }`}
     >
       {/* Selection checkbox */}
-      <label className="absolute top-3 left-3 z-10 cursor-pointer">
-        <input
-          type="checkbox"
+      <div className="absolute top-3 left-3 z-10">
+        <Checkbox
           checked={selected}
           onChange={() => onSelect(artwork.id)}
-          className="w-4 h-4 rounded-sm bg-transparent border border-white/20 accent-accent focus:ring-accent/50 cursor-pointer"
+          aria-label={`Select ${artwork.title}`}
         />
-      </label>
+      </div>
 
       {/* Thumbnail */}
       <div className="relative aspect-[4/3] bg-nova-800 overflow-hidden">