Docs still present the two-package split after the root consolidation

[mnxmnz]

As-is

• Every page lives under /core or /mobile, but the package now ships everything from a single entry (Rename packages/core to packages/react-simplikit, absorb the mobile package, add subpath imports #433). The hero, nav, and sidebar still describe the old split.
• Guides are duplicated per namespace: core and mobile each have their own installation and contributing pages.
• Sidebars are hand-written lists. The site has no sitemap and no llms.txt.

To-be

• Flat reference URLs: /hooks/useToggle.html, /components/SwitchCase.html, /utils/noop.html. Guides move to the root. Old URLs keep working through redirect stubs generated in buildEnd from the existing route definitions.
• Sidebar generated from source, grouped as Hooks, Components, Utilities, Mobile Web, with a one line description per item.
• One merged guide set in en, ko, and ja: intro, installation, design principles, SSR safety, mobile web, contributing.
• Landing leads with a single Get Started button. Add sitemap and llms.txt generation.

Out of scope

• Live demos, usage based categories, and clean URLs without the html extension. Each can land later on top of this structure.