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_dims.rs

@@ -377,3 +377,7 @@ mod tests;
 #[cfg(test)]
 #[path = "sketch_typed_intent_tests.rs"]
 mod typed_intent_tests;
+
+#[cfg(test)]
+#[path = "sketch_clover_ui_tests.rs"]
+mod clover_ui_tests;