Elefseus/dsh-default-workspace

Moves the default workspace off the system drive (DSH opens every new Session in <Documents>/deepseek-harness/default-workspace and never relocates it) while keeping stored sessions usable: rewrites the workspace record without a restart, offers the same three actions as a GUI panel, moves stored session logs together with their header cwd, and re-frames logs whose first frame is not exactly one header line. Requires the desktop host (workspaceRegistry and sessionPersistence).