Restore modal dialog contract for quick-add (role/data-state/escape),
harden package path validation, skip sensitive sessions on multi-tab
snippet sends, and show a single run-on-all-tabs action for plain snippets.
Address #2502: bind shortkeys when quick-adding snippets, add package
creation via a split + menu, convert quick-add to a right-side drawer,
and let code snippets run on all workspace tabs from the context menu.