refactor(gui,api,logging): UI layout tweaks, cleanup, and improved diagnostics

- CbBxCamType now spans the full width of CbBxCameraModel
- BtnTest_Click moved to the bottom of AiQ_GUI.cs for easier testing/navigation
- Unused using directives removed across files
- Login credentials factored out and reused in MobileAPI.cs
- VLC.cs Capture function reviewed and superseded by TakeSnapshot
- InsertCamTab implementation updated to avoid use of `var`
- Misleading '// Non-ONVIF cameras' comment corrected
- Added Level.Debug logging, accessible only to developers, for detailed diagnostics

Network.cs

@@ -97,7 +97,7 @@ namespace AiQ_GUI
             byte[] discoveryPacket =
             [
                 0x50, 0x4f, 0x4c, 0x4c, 0xaf, 0xb0, 0xb3, 0xb3,
-        0xb6, 0x01, 0xa8, 0xc0, 0x0b, 0x1a, 0x00, 0x00
+                0xb6, 0x01, 0xa8, 0xc0, 0x0b, 0x1a, 0x00, 0x00
             ];
 
             async Task SendAndListen(IPAddress localIp)