Fix dark mode text color on permissions tab empty stat (#19336) (#19340)

Before: black text in dark mode
<img width="1224" height="860" alt="image"
src="https://github.com/user-attachments/assets/a419ef77-9358-4588-ad19-a15b57448682"
/>


After updated styling: the correct grey text in dark mode
<img width="638" height="249" alt="Screenshot 2026-04-05 at 2 47 24 PM"
src="https://github.com/user-attachments/assets/bf736464-d33c-40f1-8244-2cf5d93b7e9c"
/>

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-front/src/modules/settings/components/SettingsEmptyPlaceholder.tsx

@@ -0,0 +1,35 @@
+import { styled } from '@linaria/react';
+import { type ReactNode } from 'react';
+import { themeCssVariables } from 'twenty-ui/theme-constants';
+
+type ThemeSpacingKey = keyof typeof themeCssVariables.spacing;
+
+type SettingsEmptyPlaceholderProps = {
+  children: ReactNode;
+  padding?: ThemeSpacingKey;
+  textAlign?: 'left' | 'center' | 'right';
+};
+
+const StyledPlaceholder = styled.div<{
+  placeholderPadding: string;
+  placeholderTextAlign: string;
+}>`
+  color: ${themeCssVariables.font.color.tertiary};
+  padding: ${({ placeholderPadding }) => placeholderPadding};
+  text-align: ${({ placeholderTextAlign }) => placeholderTextAlign};
+`;
+
+export const SettingsEmptyPlaceholder = ({
+  children,
+  padding = '8',
+  textAlign = 'center',
+}: SettingsEmptyPlaceholderProps) => {
+  return (
+    <StyledPlaceholder
+      placeholderPadding={themeCssVariables.spacing[padding]}
+      placeholderTextAlign={textAlign}
+    >
+      {children}
+    </StyledPlaceholder>
+  );
+};