fix(setup): source the console host from the panel hostname, not op.console

The owner setup URL and the limbo login link were built from the admin host
(op.console.<root>, with an op.console.localhost fallback) and a hardcoded
console.<root>, so an operator who set a custom panel_hostname got an unreachable setup
link and a wrong login target. Thread the resolved panel host (defaultPanelHostname)
through performSetupMCBind, the MC-bind TUI, and the login system-server env
(new FELIS_PANEL_HOSTNAME); the limbo plugin prefers it and keeps console.<root> only as
the fallback for an older operator whose env predates it. This also matters for security:
the only wired WebAuthn verifier is scoped to the panel host, so passkey enrollment must
land on the panel face, never op.console.

While here, the limbo login handler checks link status before minting a bind code: an
already-linked player is sent straight to the lobby instead of being shown a useless code.

internal/api/handlers_setup.go

@@ -11,7 +11,7 @@ import (
 // Setup-token redemption (spec §B setup bootstrap). The `felis setup` MC-bind
 // flow mints a one-time token and prints a URL like:
 //
-//	https://op.console.<root>/setup?token=<raw>
+//	https://console.<root>/setup?token=<raw>
 //
 // The Owner opens that URL in a browser; the SPA reads the token from the query
 // string and POSTs it here. This handler consumes the token (single-use, hashed