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' },
 };
 

src/components/layout/Header.tsx

@@ -3,7 +3,7 @@
  * Top navigation bar with search and actions
  */
 import { useState } from 'react';
-import { useLocation, useNavigate } from 'react-router-dom';
+import { useLocation } from 'react-router-dom';
 import { Search, Bell, Moon, Sun, Monitor } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
@@ -21,7 +21,6 @@ const pageTitles: Record<string, string> = {
 
 export function Header() {
   const location = useLocation();
-  const navigate = useNavigate();
   const theme = useSettingsStore((state) => state.theme);
   const setTheme = useSettingsStore((state) => state.setTheme);
   

src/components/layout/Sidebar.tsx

@@ -3,7 +3,7 @@
  * Navigation sidebar with menu items
  */
 import { useState, useEffect } from 'react';
-import { NavLink, useLocation } from 'react-router-dom';
+import { NavLink } from 'react-router-dom';
 import {
   Home,
   MessageSquare,
@@ -62,7 +62,6 @@ function NavItem({ to, icon, label, badge, collapsed }: NavItemProps) {
 }
 
 export function Sidebar() {
-  const location = useLocation();
   const sidebarCollapsed = useSettingsStore((state) => state.sidebarCollapsed);
   const setSidebarCollapsed = useSettingsStore((state) => state.setSidebarCollapsed);
   const devModeUnlocked = useSettingsStore((state) => state.devModeUnlocked);