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/toast.tsx

@@ -16,7 +16,7 @@ const ToastViewport = React.forwardRef<
   <ToastPrimitives.Viewport
     ref={ref}
     className={cn(
-      'fixed top-0 z-[9999] flex max-h-screen w-full flex-col-reverse p-4 sm:bottom-0 sm:right-0 sm:top-auto sm:flex-col md:max-w-[420px]',
+      'fixed top-0 z-[1001] flex max-h-screen w-full flex-col-reverse p-4 sm:bottom-0 sm:right-0 sm:top-auto sm:flex-col md:max-w-[420px]',
       className,
     )}
     {...props}