## Why
New error variants should not prevent older clients from handling app-server errors.
## What changed
- Deserialize unknown `CodexErrorInfo` strings and objects as `Other` in Rust, while preserving known variants and the `"other"` serialization.
- Allow arbitrary strings and objects in the exported JSON schemas and TypeScript type.
- Update Python SDK generation and generated models to accept unknown error strings and object payloads.
## Testing
Add Rust tests for `"other"` round trips, unknown string and object fallbacks, known structured variants, and rejection of null, boolean, numeric, and array values.
GitOrigin-RevId: 40c17896019924b2ef7970ee2205ea0154d0d1b3