fix(build): include vite/client types in tsconfig.test.json

`tsconfig.test.json` overrides `types` to `["vitest/browser"]` only,
and its `include` globs (spec/`__tests__` files) never pull in
`src/vite-env.d.ts` — the file whose `/// <reference types="vite/client" />`
normally makes `*.png` (and other Vite asset) imports resolve. Since
this narrower program's file set never processes that reference,
`@lexical`-adjacent... actually any `.tsx` reachable from a spec file
that imports a static asset (here `WelcomeHero.tsx` importing
`@/assets/logo.png`, pulled in transitively) fails type-checking with
`TS2307: Cannot find module`.

This reliably reproduced standalone (`bunx tsc -p tsconfig.test.json`,
3/3 runs) and is what failed CI's `build` job — `bun run build` runs
this tsc invocation before `vite build`. Explicitly adding
`vite/client` to the `types` array fixes it without depending on
`vite-env.d.ts` being in this program's include scope.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: koki-develop

tsconfig.test.json

@@ -1,7 +1,7 @@
 {
   "extends": "./tsconfig.json",
   "compilerOptions": {
-    "types": ["vitest/browser"]
+    "types": ["vite/client", "vitest/browser"]
   },
   "include": [
     "src/**/*.spec.ts",