Resolve conflict in client/ios/NetBirdSDK/client.go: keep v0.73.2's
thread-safe state handling (stateMu, setState, stateSnapshot) and layer
the SSH client's sshState() helper on top of stateSnapshot().
Add missing imports (strconv, internal/auth, internal/profilemanager) to
ssh_client.go that the SSH feature branch referenced but never imported.
Exposes SSHClient + SSHTerminalListener to the iOS app, mirroring the
Android binding. Connect() auto-detects the server type via banner
inspection and selects the auth path: NetBird-SSH with JWT triggers the
device-code OAuth flow via the existing URLOpener; NetBird-SSH without
JWT uses the NetBird private key; regular SSH falls back to the NetBird
key then optional password. The client dials through the running tunnel
with a plain net.Dialer and streams PTY output back to Swift via the
gomobile-bound listener for rendering in the terminal view.
Adds a config field and sshState() accessor to the iOS Client so the
SSH client can reach the active config and engine.
