test: use happy dom (#34154)

web/docs/test.md

@@ -8,7 +8,7 @@ When I ask you to write/refactor/fix tests, follow these rules by default.
 
 - **Framework**: Next.js 15 + React 19 + TypeScript
 - **Testing Tools**: Vitest 4.0.16 + React Testing Library 16.0
-- **Test Environment**: jsdom
+- **Test Environment**: happy-dom
 - **File Naming**: `ComponentName.spec.tsx` inside a same-level `__tests__/` directory
 - **Placement Rule**: Component, hook, and utility tests must live in a sibling `__tests__/` folder at the same level as the source under test. For example, `foo/index.tsx` maps to `foo/__tests__/index.spec.tsx`, and `foo/bar.ts` maps to `foo/__tests__/bar.spec.ts`.
 
@@ -30,7 +30,7 @@ pnpm test path/to/file.spec.tsx
 
 ## Project Test Setup
 
-- **Configuration**: `vitest.config.ts` sets the `jsdom` environment, loads the Testing Library presets, and respects our path aliases (`@/...`). Check this file before adding new transformers or module name mappers.
+- **Configuration**: `vite.config.ts` sets the `happy-dom` environment, loads the Testing Library presets, and respects our path aliases (`@/...`). Check this file before adding new transformers or module name mappers.
 - **Global setup**: `vitest.setup.ts` already imports `@testing-library/jest-dom`, runs `cleanup()` after every test, and defines shared mocks (for example `react-i18next`). Add any environment-level mocks (for example `ResizeObserver`, `matchMedia`, `IntersectionObserver`, `TextEncoder`, `crypto`) here so they are shared consistently.
 - **Reusable mocks**: Place shared mock factories inside `web/__mocks__/` and use `vi.mock('module-name')` to point to them rather than redefining mocks in every spec.
 - **Mocking behavior**: Modules are not mocked automatically. Use `vi.mock(...)` in tests, or place global mocks in `vitest.setup.ts`.