## What changed
- Add `features.tool_registry.error_on_tool_collisions`, defaulting to `false`, to the TOML model, generated schema, and resolved runtime configuration.
- Treat `tool_registry` as structured configuration rather than a feature toggle, including in strict config validation and profile configuration.
- Preserve the resolved collision policy in session config lockfiles when it is enabled or explicitly configured.
## Testing
- Cover deserialization, strict validation, default and enabled resolution, feature materialization, and config lockfile serialization.
GitOrigin-RevId: 2c27109dcf2a3d1e51064cc60088703e36a0f85a