Explicitly prepares and validates a reusable Obscura profile runtime.
mix obscura.profile.prepare --profile balanced --backend emily --allow-download
mix obscura.profile.prepare --profile balanced --backend emily --offline --jsonDownloads require --allow-download; otherwise preparation is cache-only.
--offline always forbids remote asset access. The task reports the effective
cache directory, model index, observed download bytes, stage transitions,
elapsed time, and final readiness. JSON mode emits one object per line and
disables Bumblebee's terminal progress bar.
Online preparation retries one transient model or tokenizer load failure. Recovery quarantines unreferenced partial cache files before downloading a clean replacement. Quarantined files remain on disk for operator review.