Accumulate OpenCode settings restarts behind Apply & Restart

Defer OpenCode reloads after settings mutations, track pending changes,
and expose a top-right Apply & Restart OpenCode action with a counter so
sessions stay available until the user explicitly applies.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/components/sections/agents/AgentsSidebar.tsx

@@ -188,6 +188,8 @@ export const AgentsSidebar: React.FC<AgentsSidebarProps> = ({ onItemSelect }) =>
       if (result.ok) {
         if (result.requiresManualRestart) {
           toast.warning(t('settings.agents.page.toast.savedManualRestart'));
+        } else if (result.restartDeferred) {
+          toast.success(t('settings.view.pendingRestart.saved'));
         } else if (confirmActionType === 'delete') {
           toast.success(t('settings.agents.sidebar.toast.agentDeleted', { name: confirmActionAgent.name }));
         } else {