Change 'Save Custom field' to 'Save Custom Field' and
'Save Custom field value' to 'Save Custom Field Value' for consistency.
Update gettext files accordingly.
Add tests to verify that copy and open-email buttons are disabled
when no members are selected and enabled after selection.
Also verify that the counter shows the correct count.
Use URI.encode_www_form() instead of URI.encode() for mailto query parameters.
This is the safer choice for query parameter encoding.
Add comment about mailto URL length limits that vary by email client.
Calculate selected_count, any_selected? and mailto_bcc once in assigns
instead of recalculating Enum.any? and Enum.count multiple times in template.
This improves render performance and makes the template code more readable.
Remove navigation attributes (href, navigate, patch) when disabled=true
to prevent 'Open in new tab' and 'Copy link' from working on disabled links.
This makes the disabled state semantically stronger and independent of CSS themes.
