Docs: reflect Phase D1 landing

Rename view_model -> view_mode_model across Design View spec docs;
archive D1 to COMPLETED.md; add view_mode_model_tests to CLAUDE.md
targets table and pure-core list.

docs/product/design-view.md

@@ -273,7 +273,7 @@ index, and is togglable per selection.
 
 Mirrors the capture pillar's split exactly.
 
-**Pure `view_model` (REAPER-free, unit-tested — the mirror of `bank_model`):**
+**Pure `view_mode_model` (REAPER-free, unit-tested — the mirror of `bank_model`):**
 - Mode registry: ordered set of modes (id, display name, ordinal); Arrange + Design
   seeded; add/query more.
 - Membership index: `track GUID → { mode ids }` (normally one; multiple only via