Add Remote Desktop (JPEG-over-WebSocket), Agent v2.2.0

- RtcService.cs: Screen capture via Graphics.CopyFromScreen, ~8fps JPEG stream over WebSocket
- shellServer.js: Separate rdp-agent/rdp types with independent socket maps (no shell collision)
- AgentDetailPage: WebSocket-based RemoteDesktop component replaces WebRTC attempt
- setup.iss: Fixed filename to include 'v' prefix (IT-Nexus-Agent-Setup-v2.2.0.exe)
- Removed SIPSorcery dependencies, added System.Drawing.Common

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/PatchManagementPage.jsx

@@ -5,7 +5,7 @@ import { useAuth } from '../context/AuthContext';
 
 const ANN_TYPES = { maintenance: { icon: '🔧', label: 'Wartung', color: '#f59e0b' }, warning: { icon: '⚠️', label: 'Warnung', color: '#ef4444' }, info: { icon: 'ℹ️', label: 'Info', color: '#6366f1' } };
 
-const LATEST_AGENT_VERSION = '2.1.2';
+const LATEST_AGENT_VERSION = '2.2.0';
 const SEVERITY_LABELS = { critical: 'Kritisch', important: 'Wichtig', moderate: 'Moderat', low: 'Niedrig', all: 'Alle' };
 const SEVERITY_COLORS = { critical: '#EF4444', important: '#F59E0B', moderate: '#3B82F6', low: '#6B7280', all: '#0D9488' };
 const COMMAND_LABELS = { check_updates: '🔍 Update-Scan', install_updates: '⬇️ Installation', reboot: '🔄 Neustart', upgrade_win11: '🪟 Win 11 Upgrade', update_agent: '⬆️ Agent-Update' };