dsh-session-hygiene: Adding a Recycle Bin, Orphan Cleanup, and Workspace Grouping to DSH Sessions

Maintained by liudapeng0311 and classified as admin-security, dsh-session-hygiene fills three gaps in the DSH sidebar: moving deleted sessions to a recoverable trash can instead of unlinking them; using Settings → Session cleanup to identify orphaned sessions left by deleted workspaces and supporting archiving or moving them to the trash; and using Settings → Workspace categories to group workspaces, perform drag-and-drop assignments, and collapse category headers. The plugin operates incrementally throughout; after uninstallation, the sidebar is restored. Data is stored only in <home>/storages/session-hygiene/, with entry.json serving as the basis for recovery. It can be installed from npm via `plugin_manager install_bundle dsh-session-hygiene`, and the host requires a restart after installation.