Function init_backends_default 

pub fn init_backends_default() -> Result<()>

Load the backend modules the way the build expects, with no caller-supplied path.

• Compiled-in builds (the default static build, or a plain shared build): a no-op returning Ok(()) — the backends are already registered.
• dynamic-backends builds: resolves the directory containing the loaded libtranscribe and scans only that directory. Ship the backend modules next to libtranscribe for this helper to find them.

If your app uses a different layout, call init_backends with that resolved module directory instead. Like init_backends, this is idempotent and must run once before the first model load.