Add business dashboard dark mode from Super Admin theme setting.

Login and in-app surfaces follow tenant themeMode, matching customer dark tokens, with themed switches and tighter card/table chrome.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/business/src/utils/applyBusinessTheme.ts

@@ -4,6 +4,25 @@ import {
   type BusinessPrimaryColorId,
 } from './businessPrimaryColors'
 
+export type DashboardThemeMode = 'light' | 'dark'
+
+export function applyThemeMode(mode: 'light' | 'dark' | undefined) {
+  document.documentElement.setAttribute(
+    'data-theme',
+    mode === 'dark' ? 'dark' : 'light',
+  )
+}
+
+export function pickThemedLogoUrl(
+  lightUrl: string | null | undefined,
+  darkUrl: string | null | undefined,
+  mode: DashboardThemeMode,
+): string | null {
+  const light = lightUrl?.trim() || null
+  const dark = darkUrl?.trim() || null
+  return mode === 'dark' ? dark || light : light
+}
+
 const CSS_VAR_DEFAULTS: Record<string, string> = {
   '--primary': '#3b82f6',
   '--primary-glow': '#3b82f6',