412edec028
/api/showcase returns a random sample; after enough scrolling, an unlucky 3-item batch can be entirely in the `seen` Set, which was flipping `exhausted=true` and surfacing "End." mid-scroll. The showcase is endless by intent — only a genuinely empty API response (library has 0 images) should mark it exhausted. Tiny-library fallback: cap retries at 8 to avoid spinning forever.