fix: send Claude identity prefix on first session message

The systemSent variable was being set to true before being passed to
runCommandReply, causing the identity prefix to never be injected.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/auto-reply/reply.ts

@@ -263,7 +263,6 @@ export async function getReplyFromConfig(
     };
     sessionStore[sessionKey] = sessionEntry;
     await saveSessionStore(storePath, sessionStore);
-    systemSent = true;
   }
 
   const prefixedBody =