Partially signed block

A block may contain invalid operations, but not necessarily this block needs to be rejected as that adds latency to the network, another option is to allow signatures over part of a block, and only the part that has enough signatures will be included.

This will happens both in the case of unknown consensus operations or unknown Tezos operations,

The issue names no files, tests, or entry points. Start by locating block validation and signature handling, then clarify how unknown operations, partial signatures, inclusion thresholds, and latency should behave. Done requires an agreed design and tests covering partially signed blocks.

Written by the indexing model from the issue text.