feat(pairing): auto-close the QR/link dialog once the device connects

The pairing session is single-use, so it leaving the pending list (polled
every 5s) means it was redeemed — close the dialog and toast success. Armed
only after the pairing has been seen in the pending list, so the stale list
at result-phase open can't blink the dialog shut; expired/cancelled sessions
close it silently. Pending-list polling now preserves the previous list on a
transient fetch failure instead of blanking it (which would also have faked
the redeem signal).

packages/ui/src/lib/api/types.ts

@@ -1109,6 +1109,8 @@ export interface RemoteClientRecord {
   expiresAt?: string | null;
   clientKind?: string | null;
   authMethod?: string | null;
+  /** Pairing session this client was created from, when authMethod is 'pairing'. */
+  pairingId?: string | null;
   deviceName?: string | null;
   devicePlatform?: string | null;
   usesRelay?: boolean;