Agent Skills: research-deep

Read an existing research outline and fan out independent background agents to deeply research each item, producing one structured JSON per item against the shared field schema. Resumable, batched, with output disabled per agent (each agent has its explicit output file). Use when `outline.yaml` + `fields.yaml` from `/research-outline` are in place and you want to parallelise the per-item investigation — academic paper deep-dives, product comparisons, benchmark fills, multi-target competitive analysis. Trigger this after `/research-outline`, before `/research-report`.