Codex gate found a SILENT hazard: if a workspace drag is abandoned without
ondragend firing (cancel/drop-outside/blur), _wsActiveDragPath lingered and a
later FOREIGN text/plain drag could be misread as a workspace move. Hardening:
- _wsDragSrcPath now only trusts the active flag when the drop's own text/plain
EQUALS _wsActiveDragPath (a foreign/empty text drag resolves to '' -> no move).
- Shared _clearWsDragData() called from ondragend, a drop finally, and
window-level dragend/drop/pagehide/blur fallbacks (lost-dragend cleanup).
- 2 regression tests (stale-flag foreign-text -> empty; _clearWsDragData resets),
proven non-vacuous.
Co-authored-by: Rod Boev <rod.boev@gmail.com>
