qcap seal (#cli-003)

[jvanulde]

Encrypt payload; write signatures/recipients.

[jvanulde]

Status: not implemented. Plan: per-file XChaCha20-Poly1305 envelope encryption, recipients key-wrapping. Subtasks: key derivation, wrapping, CLI UX, tests.

[edip-dev-01]

Addressed in fork commit edip-dev-01/q-cap@33659d9: adds qcap seal for encrypted .qcap creation with recipients, encrypted payload entries, and signatures. Pending upstream merge: edip-dev-01@33659d9

[edip-dev-01]

Closed by merged PR #39: #39