feat: add VNC support with noVNC integration

- Introduced a new VNC viewer panel in the frontend, allowing users to connect to VNC sessions.
- Implemented VNC connection handling with optional SSH tunneling in the backend.
- Added a new SSH key manager for managing SSH keys within the terminal.
- Created a trigger rules engine to monitor terminal output and trigger actions based on defined patterns.
- Added CSS styles for the VNC viewer and its components.
- Updated database schema to support VNC protocol in profiles.
- Implemented WebSocket proxy for VNC connections to facilitate communication between the frontend and backend.

internal/validation/validation.go

@@ -95,6 +95,8 @@ func ValidateProfile(p *models.Profile) error {
 		}
 	case models.ProtocolGitHub:
 		// GitHub profiles require no host-level validation beyond the common checks.
+	case models.ProtocolVNC:
+		// VNC profiles use vnc.vncHost or the profile-level host; validated at connect time.
 	default:
 		errs.Add("protocol", fmt.Sprintf("unsupported protocol %q", p.Protocol))
 	}