refactor(signature_collector): Remove base_hash

[dknopik]

Consider the comment:

        /// A hash that identifies what we are signing. Note that the actual signing root might be
        /// different - for example, because we are in different beacon chain attestation
        /// committees, and the attestation data differs therefore.
        base_hash: Hash256,

This is example incorrect. Only the actual attestation data is signed - which is the same for all validators. Therefore there is no reason for this base_hash field to exist - we can simply use the signing root for the same purpose.

Additional Info

Also renamed ValidatorSigningData to SigningData now that we also use the data within for committee signature tracking purposes.

[Copilot]

Pull Request Overview

This PR removes the base_hash field from the signature collector system, as the comment indicating it was needed for different signing roots was incorrect. The actual attestation data is the same for all validators, so the signing root can be used directly instead of maintaining a separate base hash.

• Removed base_hash parameter from SignatureRequester::Committee variant and all related function calls
• Renamed ValidatorSigningData to SigningData to reflect its broader usage beyond just validator signing
• Updated all references to use the signing root directly instead of the base hash for committee signature tracking

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
anchor/validator_store/src/lib.rs	Removed base_hash parameter from collect_signature method and all its call sites, replaced logic to use Role::Committee check instead
anchor/signature_collector/src/lib.rs	Removed base_hash field from SignatureRequester::Committee, renamed ValidatorSigningData to SigningData, updated committee signature tracking to use signing root

Comments suppressed due to low confidence (1)

anchor/validator_store/src/lib.rs:974

• This line computes data_hash but it's no longer used anywhere in the code after removing the base_hash parameter. This creates unused code that should be removed.

            };

[diegomrsantos]

Could you please explain this?