chore: pin pnpm isolated node-linker to fix svelte ts parsing

A global `node-linker=hoisted` flattens node_modules and gives svelte,
@sveltejs/kit and @sveltejs/acorn-typescript separate `acorn` copies. Since
svelte parses TypeScript via `Parser.extend(tsPlugin())`, the mismatched
Parser class hierarchy makes every `<script lang="ts">` block fail with
"Unexpected token" during `vite build`.

Pinning pnpm's default isolated linker in the repo `.npmrc` overrides any
global setting so all three packages resolve a single `acorn` instance.

.npmrc

@@ -1 +1,7 @@
 reporter=append-only
+
+# Pin pnpm's default isolated linker. A global `node-linker=hoisted` flattens the
+# tree and gives svelte, @sveltejs/kit and @sveltejs/acorn-typescript separate
+# `acorn` copies, which breaks `Parser.extend(tsPlugin())` — every `<script lang="ts">`
+# then fails to parse with "Unexpected token" during `vite build`.
+node-linker=isolated