Sort numeric labels by value

Records, zones and findings now order all-digit labels numerically, so
reverse zones list 2 before 101. model.CanonicalLess is replaced by
model.NameLess; other labels keep byte order.

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

internal/model/blocking.go

@@ -204,7 +204,7 @@ func (s *State) SortedBlockRules() []*BlockRule {
 	sort.Slice(out, func(i, j int) bool {
 		a, b := out[i], out[j]
 		if a.Name != b.Name {
-			return CanonicalLess(a.Name+".", b.Name+".")
+			return NameLess(a.Name+".", b.Name+".")
 		}
 		if a.Exact != b.Exact {
 			return !a.Exact