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/sketch/src/lib.rs

@@ -55,8 +55,8 @@ pub use profiles::{
 };
 pub use shape::{Shape, intersections};
 pub use solver::{
-    Analysis, DrivingValues, Hold, SolveReport, SolveStatus, measure_dimension, solve, solve_after_edit, solve_after_value_edit, solve_holding,
-    solve_with,
+    Analysis, CONSISTENT, DrivingValues, Hold, SolveReport, SolveStatus, constraint_residual, determined_by, measure_dimension, solve,
+    solve_after_edit, solve_after_value_edit, solve_holding, solve_with,
 };
 pub use text::{MAX_TEXT_CHARS, text_geometry, text_geometry_in};
 pub use wire::{MAX_FIT_POINTS, MAX_WIRE_POINTS, Wire, WireSpace, fit_polyline};