Rename schema lang attribute to parser

[ultmaster]

Summary

• switch parser value from expr to eval for schemas and tools
• document and test the parser="eval" attribute for response schemas and tool definitions

Testing

• npm run build-webview
• npm run build-cli
• npm run lint
• npm test
• pytest python/tests

---

https://chatgpt.com/codex/tasks/task_e_68a6680bc2fc832e8f318fbef783d1cf

[Copilot]

Pull Request Overview

This PR renames the lang attribute to parser for schema and tool definition elements, and changes the parser value from expr to eval for expression-based schemas and tools.

• Replaces all instances of lang attribute with parser in schema and tool elements
• Changes expression parser value from expr to eval
• Updates documentation and test cases to reflect the new naming convention

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
packages/poml/tests/file.test.tsx	Updates all test cases to use parser="eval" and parser="json" instead of lang="expr" and lang="json"
packages/poml/file.tsx	Updates core file processing logic to use parser attribute instead of lang and handle eval instead of expr
docs/vscode/features.md	Updates documentation examples to use parser="eval"
docs/language/standalone.md	Updates comprehensive documentation to use parser attribute and eval value throughout examples

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}