Replace __dirname with import.meta.dirname in the plugins workspace
vite configs (root paths and the plugins-runtime tsconfigPath) and in
frontend/vite.config.js, dropping the fileURLToPath fallback.
Import vite.config.iife with the explicit .ts extension in the
plugin-api-test-suite headless/tests configs and allow it in
tsconfig.node.json (moduleResolution Bundler + noEmit), matching the
mcp/packages/plugin precedent.
Remove .storybook/vitest.setup.ts and its setupFiles entry;
@storybook/addon-vitest 10.3+ provisions preview annotations
automatically.
These clear the Vite `configLoader: 'native'` warnings ahead of that
loader becoming the default.
AI-assisted-by: omen-alpha
Andrey Antukh