refactor(pairing): centralize reply formatting

src/pairing/pairing-labels.ts

@@ -0,0 +1,10 @@
+import type { PairingProvider } from "./pairing-store.js";
+
+export const PROVIDER_ID_LABELS: Record<PairingProvider, string> = {
+  telegram: "telegramUserId",
+  discord: "discordUserId",
+  slack: "slackUserId",
+  signal: "signalNumber",
+  imessage: "imessageSenderId",
+  whatsapp: "whatsappSenderId",
+};