fix: export isCommCallPlayable from useCallAudio composable

Function was used in CrmWorkspaceApp template but not exported/destructured,
causing TypeError at runtime.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/app/components/workspace/CrmWorkspaceApp.vue

@@ -277,6 +277,7 @@ const {
   callTranscriptLoading,
   callTranscriptText,
   callTranscriptError,
+  isCommCallPlayable,
   ensureCommCallWave,
   destroyCommCallWave,
   destroyAllCommCallWaves,