Allow distributors to configure trusted voice runtime paths at build time

What variant of Codex are you using?

CLI, built from source by a downstream package distributor.

What feature would you like to see?

The voice host currently requires a private GStreamer runtime located at a fixed path relative to the executable. This works for official bundled distributions, but prevents downstream source packages from using the GStreamer libraries managed by their package system.

Please provide a build-time-only way for distributors to configure the trusted GStreamer library and plugin directories (or a runtime prefix).

The default bundled-runtime behavior should remain unchanged. The mechanism should retain the current explicit plugin allowlist and canonical-path checks; this is not a request to enable arbitrary runtime discovery via GST_PLUGIN_PATH.

Additional information

This would let source-based downstream packages avoid carrying a local patch solely to redirect the voice host to their package-managed GStreamer runtime.

Start by locating the voice host's fixed GStreamer runtime path and inspect the existing explicit plugin allowlist and canonical-path checks. Review the build configuration entry points to determine how distributors can supply trusted library and plugin directories without changing the default bundled-runtime behavior; done means a downstream source build can use package-managed GStreamer safely.