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.

CONTEXT.md

@@ -239,7 +239,7 @@ the CPU reclaim; surface it at the toggle affordance (tooltip).
 ## Module architecture (preserve the pure/shell split)
 
 Pure (no REAPER types, unit-tested — the mirror of `bank_model`):
-- `view_model` — mode registry (id/name/ordinal; Arrange + Design seeded);
+- `view_mode_model` — mode registry (id/name/ordinal; Arrange + Design seeded);
   membership index (`track GUID → { mode ids }` + per-track show-both flag; add /
   remove / retag / query); **folder-tree-aware** visibility derivation (given the
   current parent↔child tree supplied by the shell + the active mode, compute the
@@ -250,7 +250,7 @@ Pure (no REAPER types, unit-tested — the mirror of `bank_model`):
 
 REAPER-facing:
 - `view` shell — reads `I_FOLDERDEPTH` across the track list to build the
-  parent↔child tree and feeds it to `view_model`; applies the planner's operations
+  parent↔child tree and feeds it to `view_mode_model`; applies the planner's operations
   via `SetMediaTrackInfo_Value` (`B_SHOWINTCP` / `B_SHOWINMIXER` / `B_MAINSEND` /
   `I_FXEN`) and `TrackFX_GetCount` + per-FX `TrackFX_SetOffline`; snapshots prior
   flag values before parking; resolves GUIDs via