fix: resolve conflicting z-index values (#788)

## Description

Currently there are various z-index values that are causing:
- Toasts to be placed behind dialog blur background
- Menu being cropped off by header

## Changes Made

- Revert `z-[1000]` back to `z-50` for the header (not exactly sure why
it was bumped)
- Refactor z-indexes over 9000 to start from 1000
- Ensure z-index of toast is higher than dialog

packages/ui/primitives/select.tsx

@@ -42,7 +42,7 @@ const SelectContent = React.forwardRef<
     <SelectPrimitive.Content
       ref={ref}
       className={cn(
-        'bg-popover text-popover-foreground animate-in fade-in-80 relative z-50 min-w-[8rem] overflow-hidden rounded-md border shadow-md',
+        'bg-popover text-popover-foreground animate-in fade-in-80 relative z-[1001] min-w-[8rem] overflow-hidden rounded-md border shadow-md',
         position === 'popper' && 'translate-y-1',
         className,
       )}