docs(ci): enable localStorage in Node.js 25 to avoid build error

Node.js 25 became "current" and our CI is now testing it. We now have a failure
because "localStorage" is now a thing in Node.js but it's not properly
enabled without the arg. So @typescript/vfs, which in the browser detects
a "localStorage" and tries to use it (but previously in Node.js wouldn't find
it so wouldn't try) finds an implementation that's incomplete.

This change activates it, so we don't get the error. But we don't really need
it, so this can be wound back when we have a fix in vfs or somewhere else in
the stack.

Ref: nodejs/node#57666
Ref: microsoft/TypeScript-Website#3449
Ref: microsoft/TypeScript-Website#3450

Author: rvagg

docs/.gitignore

@@ -20,4 +20,7 @@ pnpm-debug.log*
 # macOS-specific files
 .DS_Store
 src/content/docs/api
-.wrangler/
+.wrangler/
+
+# Node.js v25 localStorage file
+.astro-localstorage.json

docs/package.json

@@ -5,7 +5,7 @@
   "private": true,
   "scripts": {
     "dev": "astro dev",
-    "build": "astro build",
+    "build": "NODE_OPTIONS=\"--localstorage-file=.astro-localstorage.json\" astro build",
     "preview": "astro preview",
     "astro": "astro"
   },