Svelte v5 VSCode No app.html reproduction

The main branch features the bug setup with just npx sv create, npm install --save-dev sass, and creating two npm workspaces. Each vite.config.ts is extended from the root. There is a v4 branch that does not feature the bug where the only difference is the installed versions of @sveltejs/vite-plugin-svelte, svelte, and vite. There is also a no-extended-vite-config branch featuring a workaround where the vite.config.ts is duplicated rather than extended. Another workaround is available in renamed-shared-vite-config where the root vite.config.ts is renamed.