v2.4.1 — erpnext_doc_unassign + kanban unassign UX

Features

• erpnext_doc_unassign — remove one user's native assignment on any DocType via frappe.desk.form.assign_to.remove (closes the ToDo, resyncs _assign), returning the remaining open assignments. Idempotent on the Frappe side. Tool count 122 → 123.
• kanban-viewer: per-assignee unassign (×) button in the detail modal, with busy/error states.

Bug Fixes

• kanban-viewer: Frappe v16 omits _assign from single-doc GET responses — the detail modal now rebuilds it from the authoritative assignment result (assign and unassign), and treats an explicit empty _assign as truly unassigned so a just-removed assignee no longer reappears.

Full changelog: v2.4.0...v2.4.1