## What changed
- Allow namespace tool specs to contain custom freeform tools alongside function tools.
- Include namespaced custom tools in deferred tool search and expose them to code mode with names such as `editor__apply_patch`.
- Route custom payloads to matching extension tools while preserving function-only payload validation.
## Testing
- Add serialization, tool search, code-mode definition, and end-to-end dispatch coverage for namespaced custom tools.
GitOrigin-RevId: be64d35f6ae54685c5a9fcf45a732320742ea7e5