Unsafe decrypt mode

It would be possible to have the decrypt stream to be streaming. However this would emit decrypted data that hasn't been checked yet. I think there should be an unsafe decrypt mode, which can be enabled if you want this.

The issue proposes an unsafe streaming decrypt mode but names no files, tests, or entry points. Inspect the repository's decryption implementation and existing tests first, then clarify the mode's API, safety expectations, and completion criteria before estimating the implementation.

Written by the indexing model from the issue text.