Deprecate the @react-simplikit/mobile npm package

[mnxmnz]

As-is

• @react-simplikit/mobile@0.1.1 is the latest published version and carries no deprecation notice.
• README.md:15 already calls the package deprecated. npm does not, so an install prints nothing.

To-be

npm deprecate @react-simplikit/mobile "Moved into react-simplikit. Run \`npx react-simplikit-codemod mobile-to-root\` to migrate, then install react-simplikit."

• A migration section in docs/mobile/installation.md and the README note, in every locale.

Notes

• The message points at the root entry, not a react-simplikit/mobile subpath. That subpath does not exist — packages/react-simplikit/package.json has no ./mobile export and there is no src/mobile/index.ts. An earlier draft of this message named it.
• Applies to every published version: 0.0.0, 0.0.1, 0.0.2, 0.1.0, 0.1.1, and the canary tag.
• Reversible with npm deprecate @react-simplikit/mobile "", but anyone who installed in between has already seen the warning.

Depends on

• Add a codemod for migrating off @react-simplikit/mobile #454 — the deprecation message names a command, so it has to work by the time anyone reads it.