channelRows() referenced INPUT_STYLE expecting server-side substitution like
fieldRow() does, but never actually got it - it shipped as a literal
\${INPUT_STYLE} in the browser script, and nothing declared that name
client-side. Since channelRows() always renders at least one row, this threw
immediately on every plugin card, which crashed renderPlugins() (plugins list
never appeared) and crashed the post-save init() refresh too (edits looked
like they weren't taking effect). Now declares INPUT_STYLE once as a real
client-side const instead of the fragile double-escape trick, and init()
surfaces failures visibly instead of leaving the panel silently blank.