Visibility polish: admin sidebar contrast/focus, table header readability, nav focus rings

src/components/admin/admin-mobile-wrapper.tsx

@@ -36,8 +36,9 @@ export function AdminMobileWrapper({
 				<button
 					type="button"
 					onClick={() => setOpen(!open)}
-					className="flex items-center justify-center w-9 h-9 rounded-lg"
-					style={{ color: "var(--admin-text-muted)" }}
+					className="flex items-center justify-center w-9 h-9 rounded-lg
+						focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--admin-accent)] focus-visible:ring-offset-1 focus-visible:ring-offset-[var(--admin-sidebar-background)]"
+					style={{ color: "var(--admin-sidebar-text-readable)" }}
 				>
 					{open ? <X size={18} /> : <Menu size={18} />}
 				</button>