injectMediaUrl

Resolve the lazy MediaBase.objectURL promise into a string suitable for direct use in <audio src> / <img src> / <video src> / <a href download>. Returns undefined until the URL is available.

Lifecycle:

• On first read (or when media changes) the helper awaits media.objectURL, then commits the resolved string to the returned signal.
• On destroy (or when media changes) the helper calls media.revoke() to free the object URL slot. The next consumer that accesses media.objectURL mints a fresh URL from the same Blob, so live re-renders just work.
• If the underlying handle errored before settling, the promise rejects and injectMediaUrl stays at undefined. Inspect media.error to surface the failure.

Pair with injectAudio / injectImages / injectVideo / injectFiles to bridge SDK media handles into Angular templates without manual URL.createObjectURL bookkeeping.

media accepts a plain handle or a Signal<MediaBase | undefined> so callers can feed a computed(() => stream.audio()[0]).