test: assert which event type each privilege routing key decodes to

Swapping the handler for Privilege.Removed to PrivilegeAdded passed the suite, and would turn every revocation into a grant. The Setup test now asserts each key's message type, the adapter is exercised for all four events (grant then revoke), and process only accepts the four privilege event types. CLAUDE.md warns against combining Setup() with WithReconnect (per-replica queues are re-created on reconnect, losing revocations sent meanwhile).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SV1epy2pKvBx3yDfhxATk2

client.go

@@ -104,8 +104,13 @@ func (h *PrivilegeHandler) Setup() []goamqp.Setup {
 	}
 }
 
+// privilegeEvent is the set of events Process handles.
+type privilegeEvent interface {
+	UserAdded | UserRemoved | PrivilegeAdded | PrivilegeRemoved
+}
+
 // process adapts Process to a typed go-messaging-amqp handler.
-func process[T any](h *PrivilegeHandler) spec.EventHandler[T] {
+func process[T privilegeEvent](h *PrivilegeHandler) spec.EventHandler[T] {
 	return func(_ context.Context, event spec.ConsumableEvent[T]) error {
 		return h.Process(&event.Payload)
 	}