chore: Update bgAdmin.tsx to latest patterns API

[jsantell]

Summary by cubic

Updated BG Admin to the latest commontools patterns API, using typed Cells and immutable updates for safer state changes. Aligns UI interactions and handlers with the new model.

• Refactors

  • Replaced JSON schema types with Default-based TypeScript types.
  • Updated handlers to use Cell for reading/updating charms and the list immutably.
  • Removed lift component; added getRenderData and inline render.
  • Switched inline style strings to object styles.
  • Set recipe generics and name ("BG Admin").

• Dependencies

  • Fixed add-admin-charm task path in deno.json to use bgAdmin.tsx.

[cubic-dev-ai]

No issues found across 2 files