feat(server): add pairing service and notify stub

plugin/index.ts

@@ -74,4 +74,19 @@ export {
   type ServerLifecycleState
 } from "./core/runtime.js";
 
+export {
+  createPairingService,
+  PairingService,
+  type PairingRequest,
+  type PairingResult,
+  type PairingFailureReason
+} from "./services/pairing.js";
+
+export {
+  createDiscordNotificationService,
+  createMockNotificationService,
+  type DiscordNotificationService,
+  type DiscordNotificationConfig
+} from "./notifications/discord.js";
+
 export { manifest };