tests: add renderer-SDK mock layer + first 2 component-/hook-level pilots

Foundations for widening Vitest coverage past the pure-helper subset.

The real `@nitrots/nitro-renderer` eagerly loads Pixi v8 and the full
Habbo message parser/composer registry at module-import time, which
jsdom cannot host: any `tests/**` file that transitively pulled a
renderer symbol would throw before a single assertion ran. That's
why the existing 8 suites all stuck to pure modules imported by
concrete path and used `import type` for renderer-side names.

Add a stub at `tests/mocks/renderer-mock.ts`, aliased over the package
via `vitest.config.mts`. It exports:

- Explicit behavioral stubs for the symbols tests actually exercise:
  `NitroLogger`, `GetEventDispatcher`, the `mockEventDispatcher`
  helper with `addEventListener` / `removeEventListener` /
  `dispatchEvent` / `hasListeners`, and `RoomSessionDoorbellEvent`
  (signature matches the real `(type, session, userName)` to keep
  tsgo happy).
- String-keyed Proxy enums for `NitroEventType`, `RoomObjectCategory`,
  `AvatarFigurePartType`, etc. — each access returns a stable unique
  string so dispatch and listener agree.
- Lightweight `class StubClass {}` placeholders for the ~30 Pixi and
  gameplay classes the `src/api/*` barrel touches at import time
  (`NitroAlphaFilter`, `NitroContainer`, `EventDispatcher`, …).
  Keeps the cascade from throwing without simulating behavior tests
  don't care about.
- Singleton getters (`GetAssetManager`, `GetCommunication`,
  `GetSessionDataManager`, …) returning a chainable Proxy so deeply
  nested `GetX().y.z(…)` access evaluates to no-op proxies.

Pilots on top of that layer (each one designed to catch a different
class of regression):

- `tests/WidgetErrorBoundary.test.tsx` (4 cases) — happy path,
  default silent fallback + `NitroLogger.error` call, custom
  fallback node, default `unknown` widget name.
- `tests/useDoorbellState.test.tsx` (7 cases) — initial empty state,
  append on `RSDE_DOORBELL`, dedup duplicate names, remove on
  `RSDE_ACCEPTED` / `RSDE_REJECTED`, ignore stale events for
  never-pending users, full unsubscribe on unmount.

Suite count now 124/124 across 10 files (was 113/113 across 8).
`yarn typecheck` still green.

Docs: CLAUDE.md's Vitest row and "Where everything lives" pointer
updated; `docs/ARCHITECTURE.md` Tests section now lists the new
suites + a description of what the mock layer covers, and the
"Wider Vitest coverage" entry in the next-steps list is reframed
from "needs a renderer mock" to "pick the next adopter".

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/ARCHITECTURE.md

@@ -484,7 +484,7 @@ Status after this round of work:
 - Vitest 3 + jsdom + `@testing-library/react` + `@testing-library/jest-dom`
   configured. Separate `vitest.config.mts` so the runner doesn't drag in
   the renderer SDK aliases from `vite.config.mjs`.
-- **113 cases passing** across 8 test files:
+- **124 cases passing** across 10 test files. Pure-module suites:
     - `WiredCreatorTools.helpers.test.ts` (18) — formatters + snapshot
       factory.
     - `navigatorRoomCreatorStore.test.ts` (4) — Zustand store invariants
@@ -504,13 +504,40 @@ Status after this round of work:
       bail-out branches (state-not-AvatarInfoUser, mismatched
       user/roomIndex, equal-after-dedup) + the figure / favorite-group
       apply paths.
-- **Pure-module convention**: tests live in `tests/` and import from
-  concrete file paths (e.g. `../src/api/catalog/CatalogType`) rather
-  than the api barrel, so jsdom doesn't transitively load the renderer
-  SDK's Pixi-bound modules. Renderer event type imports use
-  `import type { … }` so they're erased at compile time and don't
-  trigger the runtime module load either.
-- `yarn test` + `yarn test:watch` scripts added.
+
+  Component-/hook-level suites (on the new renderer-SDK mock):
+    - `WidgetErrorBoundary.test.tsx` (4) — happy path + caught render
+      error logged via `NitroLogger.error` + custom fallback +
+      `unknown` default name.
+    - `useDoorbellState.test.tsx` (7) — initial empty state, append on
+      `DOORBELL`, dedup duplicates, remove on `RSDE_ACCEPTED` /
+      `RSDE_REJECTED`, ignore stale events, unsubscribe on unmount.
+
+- **Renderer-SDK mock at `tests/mocks/renderer-mock.ts`** —
+  `vitest.config.mts` aliases `@nitrots/nitro-renderer` over this file
+  so jsdom-hosted tests never load Pixi or the message
+  parser/composer registry. The mock exports:
+    - Explicit, behavioral stubs for the symbols tests actually
+      exercise: `NitroLogger`, `GetEventDispatcher`,
+      `mockEventDispatcher` / `clearMockEventDispatcher` helpers, the
+      `RoomSessionDoorbellEvent` class (signature mirrors the real
+      `(type, session, userName)` so `tsgo` stays happy).
+    - String-keyed `Proxy` enums for every `*EventType` /
+      `*FigurePartType` / `RoomObjectCategory` etc. — each access
+      returns a stable unique string so dispatch + listener agree.
+    - Lightweight `class StubClass {}` placeholders for the ~30 Pixi
+      and gameplay classes the `src/api/*` barrel touches at import
+      time (`NitroAlphaFilter`, `NitroContainer`, `EventDispatcher`,
+      etc.). Keeps the cascade from throwing without simulating
+      behavior tests don't care about.
+    - Singleton getters (`GetAssetManager`, `GetCommunication`,
+      `GetSessionDataManager`, …) returning a chainable proxy so
+      `GetX().y.z` evaluates to a no-op proxy instead of crashing.
+- **Pure-module convention** (still applies for non-component tests):
+  import from concrete file paths so jsdom doesn't transitively load
+  the renderer SDK; use `import type { … }` for type-only renderer
+  imports.
+- `yarn test` + `yarn test:watch` scripts.
 
 ### Logic bug fixes
 - Doorbell close button didn't close while users were pending
@@ -648,11 +675,15 @@ Remaining order of value/risk for the next contributor:
    token; the `LayoutFurniImageView` / `LayoutAvatarImageView` async
    fetch race needs a request-id ref (or is solved by migrating the
    image fetch to `useNitroQuery` keyed on props).
-6. **Wider Vitest coverage** — next worthwhile targets: the
-   `useNitroQuery` adapter (timeout + cleanup + accept-filter
-   behavior, needs a stub for `@nitrots/nitro-renderer`),
-   `useDoorbellState`/`useUserChooserState` event-reducer logic
-   (needs the same renderer stub).
+6. **Widen the component/hook Vitest coverage.** The renderer-SDK
+   mock layer is in place (`tests/mocks/renderer-mock.ts`) and the
+   first two pilots — `WidgetErrorBoundary` and `useDoorbellState` —
+   pass. Good follow-up targets: other `*State` hooks built on event
+   reducers (`useFurniChooserState`, `useUserChooserState`,
+   `useFriendRequestState`, `useChatInputState`), the `useNitroQuery`
+   adapter (timeout + cleanup + accept-filter behavior), and the
+   `LoginView` Form Actions happy/error paths. Each new test will
+   likely need to add 1-3 named exports to the renderer mock.
 
 Skipped intentionally and documented in commit messages: