Add named collection views

## Goal

Let a collection surface switch between multiple named view configurations instead of storing one layout/filter/sort setup.

## Scope

* Multiple named views for a collection surface, whether it appears inline in a block or as a full-page collection.
* Each view owns its layout, visible fields, sort, filter, search, grouping, styling, column widths, column order, and row-opening mode.
* Create, rename, duplicate, delete, and reorder views.
* A view selector for switching between views.
* A default view for the collection surface.

## Out of scope

* Sharing views across unrelated collections.
* Per-user default views.
* Permission-gated read-only views.