refactor(BillingManager): update button groups and styling for improved layout and user interaction

frontend/src/BillingManager.jsx

@@ -710,7 +710,7 @@ function BillingManager() {
               </div>
 
               {/* Быстрые фильтры */}
-              <div className="btn-group btn-group-sm" role="group">
+              <div className="btn-group" role="group">
                 <button 
                   className={`btn ${filterUrgency === '' ? 'btn-outline-primary active' : 'btn-outline-secondary'}`}
                   onClick={() => { setFilterUrgency(''); setCurrentPage(1); }}
@@ -732,7 +732,7 @@ function BillingManager() {
               </div>
 
               {/* Переключатель вида */}
-              <div className="btn-group btn-group-sm" role="group">
+              <div className="btn-group" role="group">
                 <button
                   className={`btn ${viewMode === 'cards' ? 'btn-outline-primary active' : 'btn-outline-secondary'}`}
                   onClick={() => setViewMode('cards')}
@@ -750,8 +750,8 @@ function BillingManager() {
               </div>
 
               <div className="card-actions">
-                <button className="btn btn-primary btn-sm" onClick={handleAddItem}>
-                  <IconPlus size={16} className="me-1" />
+                <button className="btn btn-primary" onClick={handleAddItem}>
+                  <IconPlus size={18} className="me-1" />
                   Добавить
                 </button>
               </div>
@@ -904,10 +904,10 @@ function BillingManager() {
                             <span className="badge bg-secondary-lt text-secondary">Неактивен</span>
                           )}
                         </td>
-                        <td>
-                          <div className="btn-list gap-1 justify-content-end flex-nowrap">
+                        <td className="text-end">
+                          <div className="btn-group" role="group">
                             <button
-                              className="btn btn-outline-success btn-sm"
+                              className="btn btn-outline-success"
                               onClick={() => {
                                 setPaymentDraft({
                                   serverId: item.id,
@@ -924,14 +924,14 @@ function BillingManager() {
                               Оплата
                             </button>
                             <button
-                              className="btn btn-outline-secondary btn-sm"
+                              className="btn btn-outline-secondary"
                               onClick={() => handleEditItem(item)}
                               title="Редактировать"
                             >
                               <IconEdit size={14} />
                             </button>
                             <button
-                              className="btn btn-outline-danger btn-sm"
+                              className="btn btn-outline-danger"
                               onClick={() => handleDeleteItem(item)}
                               title="Удалить"
                             >