V3 deterministic Minisign verification capability pack. By-value connector composition (service_kind=cli, no separate ingredient): one local minisign CLI ingredient exposes readiness plus fixed detached-signature verification with an inline public key, a trusted public-key file, or strict prehashed-signature mode. This pack is verification-only: no signing, key generation, key recreation, password changes, secret-key access, arbitrary flags, content output passthrough, or shell wrappers. Verification operations are exit-code-only; a zero exit code means the signature verified. Requires minisign on PATH (Debian/Ubuntu: apt install minisign; macOS: brew install minisign). Local and no-egress.