When images are attached, a Note/Picture toggle appears letting the user
publish as kind 20 (PictureEvent) instead of kind 1. Text input is
disabled in picture mode. Selector only shows for image file types.
Updates testing plan: Phase 1 all pass.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
nrobi144