chore: fix linting issues in ack-reaction feature

- Remove unused mock variables in tests
- Remove unused ackReactionScope variables in simple test cases
- Fix line length for ackReactionScope declaration
- All lint checks passing (0 warnings, 0 errors)
- All tests passing (8/8)

src/web/auto-reply.ts

@@ -1389,7 +1389,8 @@ export async function monitorWebProvider(
 
       // Send ack reaction after successful reply
       const ackReaction = (cfg.messages?.ackReaction ?? "").trim();
-      const ackReactionScope = cfg.messages?.ackReactionScope ?? "group-mentions";
+      const ackReactionScope =
+        cfg.messages?.ackReactionScope ?? "group-mentions";
       const shouldAckReaction = () => {
         if (!ackReaction) return false;
         if (!msg.id) return false;