dsh-timer: DSH scheduler plugin to automatically resume tasks in the original session at the scheduled time.

dsh-timer is DSH's "scheduled task" plugin, designed to address the issue where messages are executed immediately upon sending and cannot be scheduled for later execution. It allows messages to be queued for a specific time, at which point they will automatically resume execution in the original session with full access permissions. The toggle is located on the toolbar below the message input box; upon enabling it, clicking "Send" with the mouse will trigger a schedule confirmation dialog (pressing Enter will not trigger it). Users can set execution times and modes, and a "Miss Peak Hours" feature is provided to skip the two peak periods of Beijing Time (9:00–12:00 and 14:00–18:00) with one click. The task list displays real-time statuses for pending, running, completed, and failed tasks, supports canceling and clearing, and supports unlimited concurrency. Installation requires a locally running DSH and is performed via `dsh plugin --profile web add github:life1996cou/d`.