[client] tests: exercise mandatory LGMP streams

Replace legacy clipboard grant and queued input fixtures with bound SPSC
stream endpoints. Verify stream-only payload delivery, credit recovery,
release completion, and four 256 KiB records for a 1 MiB response.

Keep queue assertions for status, discovery, ownership, and control.

client/tests/CMakeLists.txt

@@ -119,7 +119,7 @@ set(LGMP_CLIPBOARD_CASES
   claim
   offer-request
   inbound-stream
-  outbound-grant
+  outbound-stream
   blocked
   cancel
   restart