"global is not defined" crash fixed in TanStack Start, React Router apps

Patch Changes

• Fix ReferenceError: global is not defined thrown from the browser Clerk loader during <ClerkProvider> startup in production builds (seen in TanStack Start and React Router apps). The loader now reads the Clerk global via globalThis instead of relying on a window.global polyfill side-effect, whose load order across bundler chunks was not guaranteed. (#8909) by @jacekradko