Keep options in a fixed order, and say which block a diff hunk is in

Options of a block (server options, a view, a zone) are listed and
written grouped by topic, alphabetical within a group, so the same
option is in the same place everywhere. Top-level statements keep the
order they were added in.

named.conf diffs add the enclosing blocks to each hunk header, like
git's function context: @@ -50,6 +49,8 @@ view "internal" {.

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

internal/model/model.go

@@ -506,7 +506,9 @@ func (s *State) ServedRecordsByZone() map[int64][]*Record {
 	return out
 }
 
-// ScopedOptions returns the options of a scope, in position order.
+// ScopedOptions returns the options of a scope: in a fixed order by name
+// for a block (see optionLess), in the order they were added for
+// top-level statements, which are written as entered.
 func (s *State) ScopedOptions(scope string, scopeID int64) []*Option {
 	var out []*Option
 	for _, o := range s.Options {
@@ -514,6 +516,10 @@ func (s *State) ScopedOptions(scope string, scopeID int64) []*Option {
 			out = append(out, o)
 		}
 	}
+	if scope != ScopeTopLevel {
+		sort.Slice(out, func(i, j int) bool { return optionLess(out[i], out[j]) })
+		return out
+	}
 	sort.Slice(out, func(i, j int) bool {
 		if out[i].Position != out[j].Position {
 			return out[i].Position < out[j].Position