Separate DSH session logs by project: @local/session-project-logs

By default, DSH session logs are stacked in `~/.dsh/sessions`, making archiving difficult when managing many projects. The `@local/session-project-logs` plugin, maintained by yyqinfo, mounts an additional official session backend for each project. This allows new sessions to be written into the project's specific `.dsh/sessions`, while historical sessions remain in the central root directory. The storage format remains unchanged, and file system links are left untouched. The article introduces the shunting mechanism, installation commands, migration of historical sessions, log verification and repair, compatibility views with path-related plugins, and considerations for cross-machine synchronization.