Glean: Picking up candidate tasks in conversation without interrupting the current topic

Glean is a DSH client plugin maintained by Morange1, responsible for registering items in conversations that merit separate handling as candidate tasks. The entire marking process does not trigger the model or consume tokens. It supports marking by clicking the bookmark button in the assistant's reply action row or using the `/candidate` command, and viewing the candidate pool via `/candidates`. The Task Desk displays candidates and dispatched tasks grouped by conversation, allowing users to open, complete, delete, or star them. Workspace write permissions are required, and task dispatching in this version is still manually recorded in the main task ledger.