Wire wake and identity into crossbar; v2 smoke and README

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

internal/limiter/limiter_test.go

@@ -32,10 +32,10 @@ func TestParallelAndQueue(t *testing.T) {
 	go func() {
 		rel, waited, err := l.Acquire(ctx, "alpha", "m")
 		if err == nil {
-			defer rel()
 			if waited < 40*time.Millisecond {
 				err = errors.New("third acquire did not wait")
 			}
+			rel() // release before reporting, so the final count check cannot race it
 		}
 		got3 <- err
 	}()