Image viewer (#609):
- The next (▶) arrow was offset from the viewport edge (right:16px) so it
floated over the 320px metadata side panel. Offset it off a shared
--fc-side-w var so it sits at the image's right edge instead; full-width
again below 900px when the panel stacks under the image.
- Arrow nav was fully disabled whenever a text field was focused. Now it
yields to the caret ONLY when the field has text; an empty tag-entry field
still navigates ←/→. Extracted to utils/textEntry.js (arrowNavAllowed).
ESC behaviour unchanged (already closes the modal, overlay-aware).
Test: arrowNavAllowed — empty/non-text → navigate, text present → don't.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
