fix: replace innerHTML with DOM API in updateCategoryOptions; restore uk.json newline

innerHTML violates project convention (PostToolUse hook blocks it); use
replaceChildren with createElement/textContent instead. Also restore the
trailing newline removed from uk.json.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/locales/uk.json

@@ -624,4 +624,4 @@
         "pendingBadgeTitle": "{{count}} нагадування",
         "pendingBadgeTitlePlural": "{{count}} нагадувань"
     }
-}
+}