Optional ReadonlyhashThe content hash the bytes must have (§76's format:
"sha256-<hex>" for the built-in digest).
Optional, because a development manifest produced before a build step genuinely has none — and an absent hash means "not verified", which is a different statement from a hash that does not match. loadFromManifest carries that distinction through: ManifestLoadOptions.requireHash is how an application says its manifest must be the verified kind.
ReadonlyurlThe URL the asset is fetched from (§79).
One manifest row: where an asset lives, and what its bytes must hash to.