[anirudhpv]

Problem

On every page load the login button and the tools that need the Analytics APIs stay in a loading state for a noticeable time before the signed-in state is known.

Cause

api.js, gsi/client and the Analytics Data/Admin API discovery docs are only requested from onInitialClientRender, i.e. after the JS bundle has downloaded, parsed and React has hydrated. On top of that, the discovery docs are only fetched after both scripts have loaded, so the slower sign-in script also delays them. All of this is sequential.

Fix

• gatsby-ssr.tsx: add an onRenderBody that injects a small inline loader into <head>. It starts loading api.js and gsi/client immediately, loads the discovery docs as soon as gapi.client is ready, and exposes the promises on window.__googleScripts.
• gatsby/onInitialClientRender.js: use the preloaded promises when present (falling back to loading the scripts itself if not), fetch the discovery docs without waiting for the sign-in script, and split the code into small helpers (loadGapi, loadGis, restoreToken). The token client setup, stored-token restore and error handling behave as before.

How tested

• yarn check-types: no new errors (the 3 existing errors on main are unrelated).
• gatsby build succeeds and the generated HTML contains the loader script in <head>.
• On a fork deployment, the time until Query Explorer leaves "Checking if you're logged in" dropped from about 4.5s to 1.8s (measured with Playwright). api.js and gsi/client now start loading about 150ms after navigation instead of after hydration.