fix(gitignore): add promptpal binary to gitignore

Prevent committing the 'pp' promptpal executable binary file.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: AnnatarHe

.gitignore

@@ -39,6 +39,8 @@ codecov.SHA256SUM
 codecov.SHA256SUM.sig
 
 model/mock_*.go
+# promptpal binary file
+pp
 promptpal.local.yml
 model/pp.types.g.go
 schema.g.json