ui: properties and status lines in words, current card on top, Use selection makes its set on OK, marks on the left (#335, #333, #360, #337, #315, #361)

- describe.rs: a definition's fields in its form's labels and units (sets by
  members and what they resolve to), for the context panel.
- reply::done: status lines that say what changed ("Showing Load deformed",
  "Mode 2: 1637 Hz", "Added material Al").
- The context panel puts the form and the selection above reports; opening
  another document clears both; what a form makes is selected.
- Use selection reuses a set with the same members, otherwise names one made
  on OK; Cancel leaves the model unchanged. The Target's set row is labelled.
- The browser's state marks sit in one column at its left edge; a right click
  selects the row its menu acts on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/ui-egui/src/form.rs

@@ -310,7 +310,7 @@ impl Form<'_> {
         let sub = join(path, &key);
         let style = self.style;
         let help = option.help_text(self.cx.units);
-        let new = fields::row(ui, &style, "", false, &help, |ui| self.scalar(ui, option, Some(&value), &sub));
+        let new = fields::row(ui, &style, option.label, false, &help, |ui| self.scalar(ui, option, Some(&value), &sub));
         if let Some(new) = new {
             obj.insert(f.key.into(), json!({key: new}));
             self.touch(path);