Merge pull request 'Fixed missing `id` attribute in `html_checkbox()`' (#585) from dandelions/snac2:pr-checkbox-id-attr into master

Reviewed-on: https://codeberg.org/grunfink/snac2/pulls/585

html.c

@@ -1451,6 +1451,7 @@ xs_html *html_checkbox(const char *form_name, const char *label, int flag)
         xs_html_sctag("input",
             xs_html_attr("type",     "checkbox"),
             xs_html_attr("name",     form_name),
+            xs_html_attr("id",       form_name),
             xs_html_attr(flag ? "checked" : "", NULL)),
         xs_html_tag("label",
             xs_html_attr("for", form_name),