Add a shared grouped action rail for Browser, Desktop, and Editor floating surface modals so modality switches, canvas docking, focus mode, New, and close controls appear in a consistent order with separators. Fix the Desktop focus button class collision that hid the canvas docking button, and align dock button labels with canvas terminology.
Add a builtin _editor plugin that owns Markdown API/WebSocket sessions, canvas and modal UI, live refresh, tabs, prompt Extras for active-context open files, inline close confirmation, and Close All handling.
Route Markdown document artifacts to Editor while keeping Office/Desktop focused on LibreOffice formats, and update Desktop/Office prompts, menus, compatibility shims, and regression coverage.
