fix(simplecue): guard declareDisjunction against over-filtering when Equals() is unreliable in CUE v0.16

In CUE v0.16, Equals() returns true for structurally-equivalent open
lists regardless of their element type: [...bool].Equals([...string])
and [...bool].Equals([]) both return true. The implicit default for any
open list is the empty closed list [].

The existing filter that strips the "default branch" from a disjunction
used `branch.Equals(defaultAsCueValue)`. For `[...bool] | [...string]`,
hasDefault=true with defaultAsCueValue=[], and both branches compared
equal to [] — so both were filtered, leaving an empty branch list.

Fix: count how many branches match the default before filtering. Only
remove a branch when exactly one branch matches — the unambiguous case
where that branch IS the default. When multiple branches match (as with
open lists in v0.16), skip filtering entirely to preserve all branches.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: moustafab

internal/simplecue/generator.go

@@ -596,9 +596,27 @@ func (g *generator) declareDisjunction(v cue.Value, hints ast.JenniesHints, defa
 	_, disjunctionBranchesWithPossibleDefault := v.Expr()
 	defaultAsCueValue, hasDefault := v.Default()
 
+	// Count how many branches equal the default value (with same reference path).
+	// In CUE v0.16+, Equals() may return true for structurally-equivalent open lists
+	// (e.g., [...bool].Equals([...string]) == true, [...bool].Equals([]) == true).
+	// To avoid over-filtering, we only remove the default branch when exactly one
+	// branch matches — otherwise we'd silently drop all branches of the disjunction.
+	matchingDefaultCount := 0
+	if hasDefault {
+		for _, branch := range disjunctionBranchesWithPossibleDefault {
+			if branch.Equals(defaultAsCueValue) {
+				_, bPath := branch.ReferencePath()
+				_, dPath := defaultAsCueValue.ReferencePath()
+				if bPath.String() == dPath.String() {
+					matchingDefaultCount++
+				}
+			}
+		}
+	}
+
 	disjunctionBranches := make([]cue.Value, 0, len(disjunctionBranchesWithPossibleDefault))
 	for _, branch := range disjunctionBranchesWithPossibleDefault {
-		if hasDefault && branch.Equals(defaultAsCueValue) {
+		if hasDefault && matchingDefaultCount == 1 && branch.Equals(defaultAsCueValue) {
 			_, bPath := branch.ReferencePath()
 			_, dPath := defaultAsCueValue.ReferencePath()