Sketch: accept redundant but consistent constraints (#687) (#699)

A clover of same-size rectangles drawn around a shared corner was refused as over-constrained.

Constraints that remove no degree of freedom but still hold (zero residual) are now kept and shown dimmed as redundant. Conflicting ones are still refused. A redundant driving dimension is refused with "already determined by ...". Typed sizes become driven (reference) dimensions. Drawing no longer adds Horizontal/Vertical to a side that is already implied through two coincident corners. The solver reports redundant constraints using a Jacobian row-dependence test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/ui-egui/src/sketch_tools.rs

@@ -1086,6 +1086,8 @@ fn glyphs(app: &SolveApp, painter: &egui::Painter, proj: &Proj, hover: Option<Po
     for (id, sp, base) in &placed {
         let Some(c) = ss.sketch.constraints.iter().find(|c| &c.id == id) else { continue };
         let failing = ss.report.failing.contains(id);
+        // Redundant (already implied by the others, but holding): dimmed, not an error.
+        let redundant = !failing && ss.report.redundant.contains(id);
         let selected = picked.as_deref() == Some(id.as_str())
             || app.session.selection.iter().any(|s| matches!(s, solidcraft_engine::Sel::SketchConstraint { id: x } if x == id));
         let lit = selected || hovered.as_deref() == Some(id.as_str());
@@ -1093,6 +1095,8 @@ fn glyphs(app: &SolveApp, painter: &egui::Painter, proj: &Proj, hover: Option<Po
             tk.error
         } else if lit {
             tk.accent
+        } else if redundant {
+            tk.glyph_text.gamma_multiply(0.45)
         } else {
             tk.glyph_text
         };
@@ -1114,7 +1118,11 @@ fn glyphs(app: &SolveApp, painter: &egui::Painter, proj: &Proj, hover: Option<Po
     if let (Some(id), Some(h)) = (hovered, hover)
         && let Some(c) = ss.sketch.constraints.iter().find(|c| c.id == id)
     {
-        let label = format!("{} ({id})", c.kind.name());
+        let label = if ss.report.redundant.contains(&id) {
+            format!("{} ({id}), redundant: already implied by other constraints", c.kind.name())
+        } else {
+            format!("{} ({id})", c.kind.name())
+        };
         let at = h + egui::vec2(12.0, 12.0);
         let g = painter.layout_no_wrap(label, egui::FontId::proportional(11.0), tk.text);
         painter.rect_filled(egui::Rect::from_min_size(at, g.size()).expand(3.0), 3.0, tk.panel);