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.

CLAUDE.md

@@ -22,13 +22,14 @@ Vendors two submodules (see `.gitmodules`):
     cmake --build build
     ctest --test-dir build
 
-Four targets:
+Five targets:
 
 | Target | Kind | Purpose |
 |---|---|---|
 | `bank_model_tests` | executable | Pure unit tests for `bank_model` — no REAPER, no DAW. |
 | `peaks_tests` | executable | Pure unit tests for `peaks` — no REAPER, no DAW. |
 | `capture_paths_tests` | executable | Pure unit tests for `capture_paths` — no REAPER, no DAW. |
+| `view_mode_model_tests` | executable | Pure unit tests for `view_mode_model` — no REAPER, no DAW. |
 | `reaper_reasampler` | loadable module | The actual extension binary (`.dll` / `.dylib` / `.so`). |
 
 ### macOS / Linux: SWELL dialog resources
@@ -48,6 +49,7 @@ There is no hot-reload. Copy the built binary into REAPER's `UserPlugins/` folde
 **Pure core (no REAPER types, unit-testable outside the DAW):**
 - `bank_model` — `Sample` metadata struct + `BankIndex` (add/remove/query/tier/dedup-by-hash + JSON round-trip). Test it hard — it is the heart.
 - `peaks` — waveform min/max bin computation from raw PCM. Fed a known signal, asserts envelope. Does not depend on REAPER's peak API.
+- `view_mode_model` — Design View mode system: mode registry, GUID-keyed membership, folder-tree-aware visibility derivation, snapshot-based park/restore planner, JSON round-trip. Mirror of `bank_model` for the Design View phase.
 
 **REAPER-facing shells:**
 - `capture` — `ICaptureBackend` interface; `OfflineRenderBackend` (deterministic default) and `RealtimeRecordBackend`. Input: `CaptureRequest`. Output: finished file + populated `Sample` handed to `bank_model`.