Factory 0.1.16: prepare inputs before delegation

Prepare accepted inputs before delegating text work, use native file tools, and assign checks and artifacts explicitly. Existing permissions and refused calls stay intact.

One Factory Opus task read prepared inputs and made the expected edit without a shell command or approval card. Package checks, 11 unit tests, staging, independent Sol Max review and required PR/main CI passed.

This is a bounded method improvement. No notification hook, approval responder, runtime or worker-isolation layer is installed. Remaining native gaps stay open in #32.

Delivered in #41. Recovery: retain the prior reviewed v0.1.15 skills and preserve local adaptations before adoption.