Review follow-ups:
- AspectRatio::toFloat() now owns the crop ratio math; CropsImageForAspectRatio
delegates to it so the enum is the single source of truth for both validation
and cropping (no more parallel literal map).
- API update controller now reloads postPlatforms before returning, so the
update response reflects the persisted platform meta/content_type (was stale).
- Tests: AspectRatio enum unit test; API valid-update read-back + 'original'
on create; MCP response read-back + valid update.
