Use JSON-key-order-agnostic assertion on signal-wait task payload

MySQL JSON column key ordering hit `workflow_tasks.payload` for the
signal-application task. Literal-array assertSame was comparing keys
in source-code order; MySQL stores them in its own internal order.
Swap to assertSameJsonObject — same pattern as the other #399 JSON
ordering fixes.

Clears 1 MySQL failure under #399:
  * testWorkflowCanWaitForSignalAndResumeAfterSignalCommand

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: durable-workflow-ops

tests/Feature/V2/V2WorkflowTest.php

@@ -4452,7 +4452,7 @@ public function testWorkflowCanWaitForSignalAndResumeAfterSignalCommand(): void
             ->where('status', TaskStatus::Ready->value)
             ->sole();
 
-        $this->assertSame([
+        $this->assertSameJsonObject([
             'workflow_wait_kind' => 'signal',
             'open_wait_id' => 'signal-application:' . $signal->id,
             'resume_source_kind' => 'workflow_signal',