claudetool/codereview: new package extracted from claudetool

Co-Authored-By: sketch <hello@sketch.dev>
diff --git a/claudetool/patch.go b/claudetool/patch.go
index 0886e66..419e966 100644
--- a/claudetool/patch.go
+++ b/claudetool/patch.go
@@ -127,7 +127,7 @@
 
 	likelyGoFile := strings.HasSuffix(input.Path, ".go")
 
-	autogenerated := likelyGoFile && isAutogeneratedGoFile(orig)
+	autogenerated := likelyGoFile && IsAutogeneratedGoFile(orig)
 	parsed := likelyGoFile && parseGo(orig) != nil
 
 	origStr := string(orig)
@@ -262,7 +262,8 @@
 	return err
 }
 
-func isAutogeneratedGoFile(buf []byte) bool {
+// IsAutogeneratedGoFile reports whether a Go file has markers indicating it was autogenerated.
+func IsAutogeneratedGoFile(buf []byte) bool {
 	for _, sig := range autogeneratedSignals {
 		if bytes.Contains(buf, []byte(sig)) {
 			return true