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>

agent-cs/setup.iss

@@ -1,5 +1,5 @@
 #define MyAppName "IT Nexus Agent"
-#define MyAppVersion "2.1.2"
+#define MyAppVersion "2.2.0"
 #define MyAppPublisher "Cereda Systems GmbH"
 #define MyAppURL "https://it-nexus.cereda-systems.de"
 #define MyAppExeName "IT-Nexus-Agent.exe"
@@ -19,7 +19,7 @@ DefaultGroupName={#MyAppName}
 DisableProgramGroupPage=yes
 DisableWelcomePage=no
 OutputDir=..\installer
-OutputBaseFilename=IT-Nexus-Agent-Setup-{#MyAppVersion}
+OutputBaseFilename=IT-Nexus-Agent-Setup-v{#MyAppVersion}
 SetupIconFile=icon.ico
 Compression=lzma2/max
 SolidCompression=yes