feat: embed appkit CLI and AI-targeted docs into the appkit and appkit-ui packages

[pkosiec]

This PR:

• consolidates all CLI tooling under a single npx @databricks/appkit command
• embeds AI-targeted documentation directly into the published packages.
• fixes double docs building on packing appkit and appkit-ui packages, which caused some race conditions

Resolves https://databricks.atlassian.net/browse/LKB-8734
Resolves https://databricks.atlassian.net/browse/LKB-8323

Testing

# From repo root
pnpm i
pnpm clean
pnpm pack:sdk

# Then install the local tarball in your test location
cd apps/dev-playground
npm install ../../packages/appkit/tmp/*.tgz --force

# Now, test the commands
npx @databricks/appkit docs
npx @databricks/appkit lint
npx @databricks/appkit generate-types
npx @databricks/appkit setup --write