dsh-session-management: Adding Archiving, Hard Deletion, and Batch Export to DSH Web Session Management

`dsh-session-management` is a session management plugin for DeepSeek Harness (DSH) Web, designed to fill the gaps in official functionality by centrally handling session archiving, deletion, and export. This plugin primarily addresses three major issues: difficulty in recovering archived sessions, the inability to truly delete local records, and time-consuming batch exports. Core features include support for archiving and unarchiving individual or batch sessions (by workspace/month); thorough deletion of local session log files from disk, with automatic skipping of running sessions to prevent data write-back; and one-click batch export of ZIP archives in a format consistent with official exports, facilitating backup or migration. The plugin provides a management window that supports grouped viewing of archived chats by workspace or month, with sorting, collapsing, batch operations, and other features. The interface supports both Chinese and English, switching automatically with the system language. Installation requires Node.js and