D048 - pack now demands only what a title is, not what a package is

Six entries are computed: the two digest tables, the digest manifest, the block-digest table, and both licences - encrypted, with the entry flags a reader needs in order to know they are.

What remains required is param.sfo, the icon, the playgo data, the name table and the key blobs. None of those is a format gap. They are the title's own content and the key material that belongs to whoever is packaging it; a format library that invented them would be inventing the title.

A test builds a package, decrypts its licence back out, and verifies the signature - so the flags, the key index, the entry row and the derivation are all checked together rather than one console-refusal at a time.