fix: forward SetTracing through Coalesce and RemappingLexer

Both wrappers hid the wrapped lexer's TracingLexer implementation,
so tracing could not be enabled through them; delegatingLexer
already forwards it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: alecthomas

coalesce.go

@@ -7,6 +7,12 @@ func Coalesce(lexer Lexer) Lexer { return &coalescer{lexer} }
 
 type coalescer struct{ Lexer }
 
+func (d *coalescer) SetTracing(enable bool) {
+	if l, ok := d.Lexer.(TracingLexer); ok {
+		l.SetTracing(enable)
+	}
+}
+
 func (d *coalescer) Tokenise(options *TokeniseOptions, text string) (iter.Seq[Token], error) {
 	it, err := d.Lexer.Tokenise(options, text)
 	if err != nil {

remap.go

@@ -16,6 +16,12 @@ func (r *remappingLexer) AnalyseText(text string) float32 {
 	return r.lexer.AnalyseText(text)
 }
 
+func (r *remappingLexer) SetTracing(enable bool) {
+	if l, ok := r.lexer.(TracingLexer); ok {
+		l.SetTracing(enable)
+	}
+}
+
 func (r *remappingLexer) SetAnalyser(analyser func(text string) float32) Lexer {
 	r.lexer.SetAnalyser(analyser)
 	return r