fix(ui): preserve construction tools and dashed feedback (#600)

Construction (X) keeps the active sketch tool, its picked points and inline values while switching line type, and drawing previews and hover show the same dashed pattern as committed construction and centre lines. Fixes #584 and #581.

Co-authored-by: lillith <35337584+0xlillith@users.noreply.github.com>

crates/ui-egui/src/lib.rs

@@ -511,6 +511,12 @@ impl SolveApp {
             self.tree.capture_prompt = Some(id.to_string());
             return;
         }
+        // A line-type toggle changes the current drawing, including a partly picked shape.
+        // Handle it before cancelling tools or inline dimensions.
+        if id == "sketch.construction" {
+            sketch_palette::toggle_construction(self);
+            return;
+        }
         dim_view::cancel();
         self.tool = None;
         self.home.open = false;
@@ -542,12 +548,6 @@ impl SolveApp {
             let edges = self.session.selection.iter().any(|s| matches!(s, solidcraft_engine::Sel::Edge { .. }));
             return self.start(if edges { "solid.fillet" } else { "solid.extrude" });
         }
-        // Construction toggle: selected sketch curves switch at once, otherwise pick them.
-        // Construction (X): convert the selection, or switch construction mode; no pick tool.
-        if id == "sketch.construction" {
-            sketch_palette::toggle_construction(self);
-            return;
-        }
         if let Some(spec) = solidcraft_engine::find_command(id)
             && (tools::Tool::for_command(id).is_some() || dialogs::Dialog::for_command(self, id).is_some())
             && id != "sketch.create"