Queue Browser needs queue search, sorting, and empty-queue filtering

## Problem

The Queue Browser lists every queue of the selected topic in one unbounded table. For large topics with many queues, operators currently scroll through the whole list to find a broker or queue. There is no broker/queue search, no way to sort queues by backlog, and no way to hide empty queues, even though the UI already receives `brokerName`, `queueId`, `minOffset`, and `maxOffset` for every queue.

This is especially common when diagnosing uneven writes: the interesting queues are the ones with the largest backlog, while empty queues add noise.

## Expected behavior

- filter queues by broker name and queue ID as the operator types;
- allow sorting by broker, queue ID, and message backlog;
- provide an "only non-empty queues" toggle;
- keep the pull-at-offset behavior unchanged;
- show the count of displayed queues separately from the total queues and total messages so filtering does not make the topic-wide totals misleading;
- include regression tests for search, sorting, and empty-queue filtering.

Start at the Queue Browser implementation and trace the existing queue data, including brokerName, queueId, minOffset, maxOffset, and the pull-at-offset behavior. Add search, sorting, the non-empty toggle, separate displayed and total counts, and regression coverage for search, sorting, and empty-queue filtering; done means all expected behaviors work without changing offset pulls.

Written by the indexing model from the issue text.