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/components/CategoryTreeSelect.module.css

@@ -11,7 +11,7 @@
   gap: 6px;
   min-height: var(--field-height);
   padding: 0 var(--field-padding-x);
-  background: rgba(255, 255, 255, 0.7);
+  background: var(--surface);
   border: 1px solid rgba(148, 163, 184, 0.35);
   border-radius: var(--radius-sm);
   transition: border-color 0.2s, box-shadow 0.2s;
@@ -84,7 +84,7 @@
   overflow-y: auto;
   margin-top: 0;
   padding: 4px;
-  background: rgba(255, 255, 255, 0.98);
+  background: var(--elevated-surface);
   border: 1px solid var(--glass-border);
   border-radius: var(--radius-sm);
   box-shadow: 0 10px 28px rgba(31, 38, 135, 0.14);