Function has_source

pub fn has_source(
    path: &Path,
    tag: Option<&str>,
    sidecar: Option<&Path>,
) -> bool

Lightweight presence hint for catalog presentation, without opening audio or sidecar text.

Bounded cached tag words or a nonempty regular adjacent LRC are sufficient. Sidecar content and current audio identity are validated only by read_current; a hint may become stale or refer to metadata-only text. No acquisition is performed. A catalogued sidecar takes precedence over discovering a newly downloaded one.