feat: add gameplay assists and variant generator

CHANGELOG.md

@@ -4,6 +4,19 @@ All notable changes are documented here.
 
 ## Unreleased
 
+- Added optional digit-completion counts with muted complete digits and red
+  over-completion warnings.
+- Added toggleable Ctrl/Command-click matching-digit highlights without turning
+  the highlights into an editable multi-selection.
+- Fixed cage replacement and removal in the setter so overlapping cages cannot
+  remain accidentally active.
+- Replaced ambiguous V/X pair labels on the board with numbered 5/10 badges and
+  gave inequalities a directional chevron with a marked lesser-value tip.
+- Added thirteen uniquely checked built-in examples covering every supported
+  constraint family.
+- Added bounded, seedable generation for classic and twelve variant families,
+  plus independent uniqueness and evidence-based difficulty assessment.
+
 ## 0.1.0 - 2026-08-30
 
 - Initial local-first Sudoku setting, playing, solving and analysis workbench.