This ticket wires up the inline apply path: ops that must be serialized (e.g. standalone DDL/commands) are applied on the dispatcher thread after a drain, then published via a synthetic completed in-flight batch.

This ticket should include:

• Drain the worker threads, then apply the op inline on the dispatcher thread by calling the shared apply path directly (applyWorkItem).
• Insert a synthetic InflightBatch with a zero remaining-workers counter and the op's optime, then wait for the advancer to pop and publish it via _waitForAdvancerIdle. Workers resume after the publish.