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/ui/Checkbox.jsx

@@ -0,0 +1,113 @@
+import React, { forwardRef } from 'react'
+
+/**
+ * Nova Checkbox – fully custom rendering (appearance-none + SVG tick).
+ * Avoids @tailwindcss/forms overriding the checked background colour.
+ *
+ * @prop {string}         label   - label text rendered alongside the box
+ * @prop {string}         hint    - small helper line below label
+ * @prop {string}         error   - inline error
+ * @prop {number|string}  size    - pixel size (default 18)
+ * @prop {string}         variant - 'accent' | 'emerald' | 'sky'
+ */
+const variantStyles = {
+  accent:  { checked: '#E07A21', ring: 'rgba(224,122,33,0.45)' },
+  emerald: { checked: '#10b981', ring: 'rgba(16,185,129,0.45)' },
+  sky:     { checked: '#0ea5e9', ring: 'rgba(14,165,233,0.45)'  },
+}
+
+const Checkbox = forwardRef(function Checkbox(
+  { label, hint, error, size = 18, variant = 'accent', id, className = '', checked, disabled, onChange, ...rest },
+  ref,
+) {
+  const dim     = typeof size === 'number' ? `${size}px` : size
+  const numSize = typeof size === 'number' ? size : parseInt(size, 10)
+  const inputId = id ?? (label ? `cb-${label.toLowerCase().replace(/\s+/g, '-')}` : undefined)
+  const colors  = variantStyles[variant] ?? variantStyles.accent
+
+  // Tick sizes relative to box
+  const tickInset    = Math.round(numSize * 0.18)
+  const strokeWidth  = Math.max(1.5, numSize * 0.1)
+
+  return (
+    <div className="flex flex-col gap-1">
+      <label
+        className={[
+          'inline-flex items-start gap-2.5 select-none',
+          disabled ? 'opacity-50 cursor-not-allowed' : 'cursor-pointer',
+        ].join(' ')}
+      >
+        {/* Hidden native input keeps full a11y / form submission */}
+        <input
+          type="checkbox"
+          id={inputId}
+          ref={ref}
+          checked={checked}
+          disabled={disabled}
+          onChange={onChange}
+          className="sr-only"
+          aria-invalid={!!error}
+          {...rest}
+        />
+
+        {/* Visual box */}
+        <span
+          aria-hidden="true"
+          style={{
+            width: dim,
+            height: dim,
+            minWidth: dim,
+            minHeight: dim,
+            aspectRatio: '1 / 1',
+            marginTop: label ? '1px' : undefined,
+            backgroundColor: checked ? colors.checked : 'rgba(255,255,255,0.06)',
+            borderColor:     checked ? colors.checked : 'rgba(255,255,255,0.25)',
+            boxShadow:       checked ? `0 0 0 0px ${colors.ring}` : undefined,
+            transition: 'background-color 150ms, border-color 150ms',
+          }}
+          className={[
+            'shrink-0 inline-flex items-center justify-center',
+            'rounded-md border',
+            className,
+          ].join(' ')}
+        >
+          {/* SVG tick — only visible when checked */}
+          <svg
+            viewBox="0 0 12 12"
+            fill="none"
+            style={{
+              width:   numSize - tickInset * 2,
+              height:  numSize - tickInset * 2,
+              opacity: checked ? 1 : 0,
+              transition: 'opacity 100ms',
+            }}
+            aria-hidden="true"
+          >
+            <path
+              d="M1.5 6l3 3 6-6"
+              stroke="white"
+              strokeWidth={strokeWidth}
+              strokeLinecap="round"
+              strokeLinejoin="round"
+            />
+          </svg>
+        </span>
+
+        {(label || hint) && (
+          <span className="flex flex-col gap-0.5">
+            {label && <span className="text-sm text-white/90 leading-snug">{label}</span>}
+            {hint  && <span className="text-xs text-slate-500">{hint}</span>}
+          </span>
+        )}
+      </label>
+
+      {error && (
+        <p role="alert" className="text-xs text-red-400" style={{ paddingLeft: `calc(${dim} + 0.625rem)` }}>
+          {error}
+        </p>
+      )}
+    </div>
+  )
+})
+
+export default Checkbox