Report the exec-server release version in environment info (#42270)

## Why

Clients need the executor's release version to make version-based compatibility decisions.

## What changed

- Add `executorVersion` to `EnvironmentInfo` and return it from both `initialize` and `environment/info`.
- Resolve the package release version at process startup so the advertised value remains stable for the server's lifetime.
- Use `0.0.0` when the version is unknown or omitted by a legacy executor.

## Testing

- Cover packaged and source-build initialization, startup caching, protocol serialization, and client-side metadata caching.

GitOrigin-RevId: a0c7f0b701a8e7e50345cd5fb1b5c5d2d38ff3b1

codex-rs/cli/src/main.rs

@@ -1036,6 +1036,7 @@ fn stage_str(stage: Stage) -> &'static str {
 }
 
 fn main() -> anyhow::Result<()> {
+    codex_build_info::initialize!();
     let remote_control_disabled = codex_app_server::take_remote_control_disabled_env();
     arg0_dispatch_or_else(move |arg0_paths: Arg0DispatchPaths| async move {
         cli_main(arg0_paths, remote_control_disabled).await?;