fix: Improve UX with searchable selects and higher modal z-index

✅ Issue 1: Modal Z-Index Fixed
- Increased dialog z-index: z-[9999] → z-[99999]
- Now properly appears above fullscreen mode (z-50)

✅ Issue 2: Searchable Select for Large Lists
- Replaced Select with SearchableSelect for:
  - Countries (200+ options)
  - Currencies (100+ options)
  - Timezones (400+ options)
- Users can now type to search instead of scrolling
- Better UX for large datasets

✅ Issue 3: Input Type Support
- Input component already supports type attribute
- No changes needed (already working)

✅ Issue 4: Timezone Options Fixed
- Replaced optgroup (not supported) with flat list
- SearchableSelect handles filtering by continent name
- Shows: 'Asia/Jakarta (UTC+7:00)'
- Search includes continent, city, and offset

📊 Result:
- ✅ Modal always on top
- ✅ Easy search for countries/currencies/timezones
- ✅ No more scrolling through hundreds of options
- ✅ Better accessibility

Addresses user feedback issues 1-4

admin-spa/src/components/ui/dialog.tsx

@@ -19,7 +19,7 @@ const DialogOverlay = React.forwardRef<
   <DialogPrimitive.Overlay
     ref={ref}
     className={cn(
-      "fixed inset-0 z-[9999] bg-black/80  data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0",
+      "fixed inset-0 z-[99999] bg-black/80  data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0",
       className
     )}
     {...props}
@@ -36,7 +36,7 @@ const DialogContent = React.forwardRef<
     <DialogPrimitive.Content
       ref={ref}
       className={cn(
-        "fixed left-[50%] top-[50%] z-[9999] grid w-full max-w-lg translate-x-[-50%] translate-y-[-50%] gap-4 border bg-background p-6 shadow-lg duration-200 data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[state=closed]:slide-out-to-left-1/2 data-[state=closed]:slide-out-to-top-[48%] data-[state=open]:slide-in-from-left-1/2 data-[state=open]:slide-in-from-top-[48%] sm:rounded-lg",
+        "fixed left-[50%] top-[50%] z-[99999] grid w-full max-w-lg translate-x-[-50%] translate-y-[-50%] gap-4 border bg-background p-6 shadow-lg duration-200 data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[state=closed]:slide-out-to-left-1/2 data-[state=closed]:slide-out-to-top-[48%] data-[state=open]:slide-in-from-left-1/2 data-[state=open]:slide-in-from-top-[48%] sm:rounded-lg",
         className
       )}
       {...props}