feat(gateway): enhance gateway process management with auto-reconnection

Improve Gateway lifecycle management with the following features:

- Add exponential backoff reconnection (1s-30s delay, max 10 attempts)
- Add health check monitoring every 30 seconds
- Add proper restart method with graceful shutdown
- Handle server-initiated notifications (channel status, chat messages)
- Add 'reconnecting' state for better UI feedback
- Enhance IPC handlers with isConnected and health check endpoints
- Update preload script with new event channels
- Improve type safety and error handling throughout

Also fixes several TypeScript errors and unused variable warnings.

src/components/common/StatusBadge.tsx

@@ -5,7 +5,7 @@
 import { cn } from '@/lib/utils';
 import { Badge } from '@/components/ui/badge';
 
-type Status = 'connected' | 'disconnected' | 'connecting' | 'error' | 'running' | 'stopped' | 'starting';
+export type Status = 'connected' | 'disconnected' | 'connecting' | 'error' | 'running' | 'stopped' | 'starting' | 'reconnecting';
 
 interface StatusBadgeProps {
   status: Status;
@@ -20,6 +20,7 @@ const statusConfig: Record<Status, { label: string; variant: 'success' | 'second
   stopped: { label: 'Stopped', variant: 'secondary' },
   connecting: { label: 'Connecting', variant: 'warning' },
   starting: { label: 'Starting', variant: 'warning' },
+  reconnecting: { label: 'Reconnecting', variant: 'warning' },
   error: { label: 'Error', variant: 'destructive' },
 };