Stack Views: ID-addressable permalink that resolves to the live view definition

Add a stable URL form for a saved Stack View that references the view by its identity (view ID or slug) rather than encoding the expanded filter/search/sort state in the query string. Loading the permalink should resolve to the view's current definition, so the link stays correct after the view's filters are edited.

Example of the desired behaviour: .../stacks?view=<viewId> (or a slug equivalent) loads whatever that view is currently defined as — instead of today's .../stacks?filterKeys=...&filterTypes=... which snapshots the filter state at copy time.