skip user replay

Closes agentclientprotocol#381.
Relates to agentclientprotocol#348.

In agentclientprotocol#348 I added replay to handle queued prompts.
In Tidewave, we ignore user_message_chunks, so I did not experience
the issue when testing. But clients that show the user_message_chunk
like Zed showed the replayed content. This commit ensures that replayed
messages are skipped.

Author: SteffenDE

src/acp-agent.ts

@@ -695,6 +695,10 @@ export class ClaudeAcpAgent implements Agent {
                 // the loop of the next prompt continues running
                 return { stopReason: "end_turn" };
               }
+              if ("isReplay" in message && message.isReplay) {
+                // not pending or unrelated replay message
+                break;
+              }
             }
 
             // Store latest assistant usage (excluding subagents)