Add a multi-select mode to the "Add project directory" dialog: each
directory row gets a select toggle (checkbox icon, Space toggles the
highlighted row), and the primary action becomes "Add selected" and
registers every selected directory in one store update. Selections apply
to the currently browsed directory and reset on navigation, dialog open,
and clone-mode entry. Clone mode keeps its single-target flow.
Add addProjects() to useProjectsStore: validates, normalizes, and dedups
paths (already-added or duplicated), creates entries in a single state
update and single persist, activates the first newly added project, and
discovers icons for each entry. Mirrors addProject semantics for the
single entry.
Refs OPE-142
Serhii Dziupin
04c37d32a5