Add tool registry collision policy configuration (#36954)

## 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

codex-rs/thread-manager-sample/src/main.rs

@@ -295,6 +295,7 @@ fn new_config(model: Option<String>, arg0_paths: Arg0DispatchPaths) -> anyhow::R
         web_search_config: None,
         experimental_request_user_input_enabled: true,
         update_plan_enabled: true,
+        tool_registry: Default::default(),
         code_mode: Default::default(),
         use_experimental_unified_exec_tool: false,
         background_terminal_max_timeout: 300_000,