feat: expand discovery with systemd services, LXC/VMs, SSH terminal, and filebrowser

- Add systemd service discovery to backend
- Add Proxmox LXC/VM detection
- Add hostType field to config for better host categorization
- Fix SSH trust between hosts (ubuntu/grizzley -> truenas/proxmox)
- Add SSH terminal support via xterm.js
- Add filebrowser for browsing host filesystems
- Update frontend types and components for new node types

server/routes/terminal.ts

@@ -0,0 +1,60 @@
+import { Router } from 'express';
+import { execSync } from 'child_process';
+import { homedir } from 'os';
+import { getHostConfigs } from '../config';
+
+const router = Router();
+
+interface TerminalRequest {
+  host: string;
+  command: string;
+}
+
+router.post('/terminal/exec', async (req, res) => {
+  try {
+    const { host: hostName, command }: TerminalRequest = req.body;
+    
+    if (!hostName || !command) {
+      return res.status(400).json({ error: 'Missing host or command' });
+    }
+
+    const hosts = getHostConfigs();
+    const hostConfig = hosts.find(h => h.name === hostName);
+    
+    if (!hostConfig) {
+      return res.status(404).json({ error: `Host not found: ${hostName}` });
+    }
+
+    const keyPath = (hostConfig.sshKeyPath || `${homedir()}/.ssh/id_ed25519`).replace(/^~/, homedir());
+    const keyArg = `-i ${keyPath}`;
+    const portArg = hostConfig.sshPort && hostConfig.sshPort !== 22 ? `-p ${hostConfig.sshPort}` : '';
+    
+    const fullCommand = `ssh -o ConnectTimeout=10 -o StrictHostKeyChecking=no ${keyArg} ${portArg} ${hostConfig.sshUser}@${hostConfig.ip} ${command} 2>&1`;
+    
+    const output = execSync(fullCommand, { encoding: 'utf-8', timeout: 30000 });
+    
+    res.json({ output, error: null });
+  } catch (error: any) {
+    res.status(500).json({ 
+      output: '', 
+      error: error.message || 'Command execution failed' 
+    });
+  }
+});
+
+router.get('/terminal/hosts', async (_req, res) => {
+  try {
+    const hosts = getHostConfigs();
+    res.json({ 
+      hosts: hosts.map(h => ({
+        name: h.name,
+        ip: h.ip,
+        user: h.sshUser
+      }))
+    });
+  } catch (error: any) {
+    res.status(500).json({ error: error.message });
+  }
+});
+
+export default router;