Was duplicating categoryFilter/projectFilter useState + filter logic in every
view (Board/List/Today/Shared/Assigned/Dispatch). Moved to one global context
(same pattern as SearchContext) with a single <TaskFilterBar/> drop-in, and
added the missing List filter dimension on top.
List filter is deliberately omitted (showList=false) on ListView, Shared,
Assigned, and Dispatch -- ListView is already scoped to one list by its
route, and the other three show tasks whose list_id doesn't belong to the
viewer's own lists (shared tasks live in their owner's lists; assigned tasks
are always unfiled after transfer; dispatch is cross-user) -- filtering any
of them by "my lists" could only ever return zero results.