fix: Allow emoji-only status changes without text
When creating a new status with only an emoji change (no text), the
validation was incorrectly showing 'No changes'. Fixed by:
1. Properly handling the case where there's no current status (emoji is null)
2. Triggering validation after emoji selection from picker
3. Only disabling submission when the new status is identical to existing
Fixes #56
Co-authored-by: nate nowack <zzstoatzz@users.noreply.github.com>