Settings Tab: Empty API Keys State

As discussed in today's design review, here's the empty state for generating API keys in settings

CC @tanmoyAtb @juans-chainsafe

Start by reviewing the attached empty-state design from the design review and searching the repository for the settings and API-key UI. No files, tests, or implementation entry points are named in the issue, so identify the relevant frontend area before planning the work. Done means the settings tab presents the API-key empty state shown in the design.

Written by the indexing model from the issue text.