fix(pairing): add auth token input for non-loopback websocket

[DonPrus]

Summary

• add an optional auth_token input on the pairing screen
• append token query param to WebSocket URLs when the token field is provided
• redact token in diagnostics modal output to avoid leaking secrets in UI
• document the non-loopback token flow in README and operations docs

Why this is the right fix for #2

• keeps the endpoint field simple (ws://host:port/ws) and removes the need for users to manually craft query params
• still supports existing URLs that already include ?token=... (does not overwrite them)
• works for local pairing, reconnects, and session restore flows

Testing

• npm run test
• npm run check
• npm run build

Closes #2