Improve Set-Struktur editor: show parent set inline, clamp long descriptions

Removes the per-row indentation (span.ind) in favor of a small "belongs to
set" tag shown above each row's title, so membership is visible without
tracing indentation depth even while sets are expanded. Description text
is now clamped to 2 lines with ellipsis by default and expands to a
scrollable ~12-line view on click.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Fuchs/wwwroot/web/fis.inv.css

@@ -650,12 +650,29 @@ table.if td.num {
   display: inline-block;
   width: 1rem;
 }
-.modal .setstruct div.sblock table.stbl td.ttl span.ind {
-  display: inline-block;
-}
 .modal .setstruct div.sblock table.stbl td.ttl span.seti {
-  margin-right: 0.3rem;
+  display: block;
+  margin-bottom: 0.15rem;
   color: #888;
+  font-size: 0.75rem;
+}
+.modal .setstruct div.sblock table.stbl td.ttl span.seti::before {
+  content: "↳ ";
+}
+.modal .setstruct div.sblock table.stbl td.ttl span.txt {
+  display: -webkit-box;
+  -webkit-box-orient: vertical;
+  -webkit-line-clamp: 2;
+  overflow: hidden;
+  white-space: normal;
+  line-height: 1.3rem;
+  cursor: pointer;
+}
+.modal .setstruct div.sblock table.stbl td.ttl span.txt.exp {
+  -webkit-line-clamp: unset;
+  display: block;
+  max-height: 15.6rem;
+  overflow-y: auto;
 }
 .modal .setstruct div.sblock table.stbl td.ttl span.cnt {
   color: #999;