Add Recommerce and Buy Back to the showcase

[Jean-crack]

Summary

Add the Recommerce apps, Recommerce and Buy Back, to the Skybridge showcase using the same structure as the existing Awaze entry.

Requested changes

• Add showcase cards for:
  • Recommerce
  • Buy Back
• Follow the same pattern/structure used for the Awaze showcase entry in docs/showcase.mdx
• Add dedicated showcase pages if needed, consistent with the current showcase layout

Context

Recommerce is approved to be cited in the README/showcase section for Skybridge.

Acceptance criteria

• Both Recommerce apps appear in the showcase
• The implementation matches the structure and level of detail used for Awaze
• Links and assets are wired consistently with the other showcase apps