Each ML data request of up to 200 files is now tried on its own. A request
that still fails after its retries is logged, its files are written with the
reason in `mlDataError`, and the command exits 1 once the dump is complete.
`fetchMLData`, used only here, is removed in favour of a per-batch loop over
`fetchMLDataBatch`.
Model: opus-5-5
Adds the machine-learning (magic) data layer: fetches per-file ML payloads (face detections + CLIP embeddings) via the existing metadata-backup fetch through the metadata pool after each refresh, decrypts and gunzips them, and stores one mldata/<fileID>.json per file by rename (present-means-complete). A derived index (mldata/clip.f32 + clip.json) loads in one read and is rebuilt whenever it disagrees with the payloads on disk in either direction, so an interrupted backfill self-heals. Never in metadata.json; incremental on later refreshes; progress via onProgress/status.
Model: opus-4-8
clawbot