Use cookies for dark mode

(also reverts most back-end changes from previous commit)

routes/web.php

@@ -69,3 +69,12 @@ Route::group(['middleware' => 'auth'], function () {
         Route::get('forget-social-login/{id}', 'AccountController@forgetSocialLogin')->name('forget-identity');
     });
 });
+
+Route::post('toggle-dark-mode', function () {
+    if (dark_mode()) {
+        setcookie('dark_mode', '0', time() - 1);
+    } else {
+        setcookie('dark_mode', '1');
+    }
+    return redirect()->back();
+})->name('toggle-dark-mode');