dsh-side-workspace: DSH Side Sessions and Right-Side Workspace

dsh-side-workspace is an open-source plugin designed for DSH agent workflows, aimed at solving the problem of the main session being fragmented by side issues, keeping the main thread focused. The plugin provides four core features: first, side-session support, which launches resumable background sessions via the `/side` command or handles one-off read-only questions via the `/btw` command; second, an integrated workspace on the right side, combining the Side (side sessions), Subagents, and Goal sections for centralized state management; third, a pinned summary mini-board for recording stage-level conclusions, with goal syncing done only manually; and fourth, a best-effort sidebar collapse hot zone. The plugin uses a bundle-type installation mode and must be mounted via a profile, followed by restarting the dsh web service. It is suited for users who wish to handle side issues in a structured manner.