fix: resolve hotkey registration failures and renderer crash

- Change default hotkey from Super+Shift+A to Alt+Shift+A — Win key
  combinations are frequently reserved by the OS and fail to register
- Make quick prompt window creation lazy (first hotkey press) so it
  cannot interfere with main window startup
- Track failed accelerators to prevent error log spam from repeated
  workspace-updated events
- Fix process.platform crash in renderer SettingsPanel — use isMac
  from @renderer/lib/platform instead (renderer has no node globals)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/renderer/components/SettingsPanel.tsx

@@ -8,6 +8,7 @@ import { LspProfileEditor } from '@renderer/components/settings/LspProfileEditor
 import { McpServerEditor } from '@renderer/components/settings/McpServerEditor';
 import { WorkspaceAgentEditor } from '@renderer/components/settings/WorkspaceAgentEditor';
 import { getElectronApi } from '@renderer/lib/electronApi';
+import { isMac } from '@renderer/lib/platform';
 import type { SidecarCapabilities, QuotaSnapshot } from '@shared/contracts/sidecar';
 import type { DiscoveredMcpServer, DiscoveredToolingState } from '@shared/domain/discoveredTooling';
 import { listAcceptedDiscoveredMcpServers, listPendingDiscoveredMcpServers } from '@shared/domain/discoveredTooling';
@@ -1328,14 +1329,15 @@ function QuickPromptSettingsSection({
   onUpdate?: (patch: Partial<QuickPromptSettings>) => void;
 }) {
   const enabled = settings?.enabled ?? true;
-  const hotkey = settings?.hotkey ?? 'Super+Shift+A';
+  const hotkey = settings?.hotkey ?? 'Alt+Shift+C';
   const defaultModel = settings?.defaultModel;
   const defaultReasoning = settings?.defaultReasoningEffort;
 
   const hotkeyDisplay = hotkey
-    .replace('Super', process.platform === 'darwin' ? '⌘' : 'Win')
+    .replace('Super', isMac ? '⌘' : 'Win')
+    .replace('Alt', isMac ? '⌥' : 'Alt')
     .replace('Shift', '⇧')
-    .replace('+', ' + ');
+    .replace(/\+/g, ' + ');
 
   return (
     <div>