Fork choice

[turuslan]

https://github.com/leanEthereum/leanSpec/blob/main/docs/client/forkchoice.md

https://github.com/leanEthereum/leanSpec/tree/main/tests/lean_spec/subspecs/forkchoice

[Copilot]

Pull Request Overview

Implements fork choice logic and adds comprehensive unit tests for vote targeting, head selection, attestation validation/processing, and time advancement per the linked spec.

• Add ForkChoiceStore core logic (safe target, head updates, attestation processing, time ticking) and helper API.
• Introduce supporting types/constants (ValidatorIndex, Interval, ceilDiv, Checkpoint::from) and wire into build.
• Add unit tests covering fork-choice behaviors and time advancement scenarios.

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
vcpkg-overlay/qtils/portfile.cmake	Bump qtils port to v0.1.5 to use updated test/outcome utilities.
src/blockchain/fork_choice.hpp	New public API and data structures for fork choice.
src/blockchain/fork_choice.cpp	Implementation of fork choice logic (safe target, head update, attestation handling, time ticking, and head selection).
src/utils/ceil_div.hpp	New ceilDiv utility.
src/types/checkpoint.hpp	Default-initialize slot; add Checkpoint::from factory.
src/types/block.hpp	Allow setHash() on const Blocks by making hash cache mutable.
src/types/constants.hpp	Add second-based slot/interval constants.
src/types/slot.hpp	Add Interval alias.
src/types/validator_index.hpp	Add ValidatorIndex alias.
src/types/vote.hpp	Default-initialize validator_id and slot.
src/blockchain/CMakeLists.txt	Link new fork_choice.cpp into blockchain lib.
tests/unit/blockchain/fork_choice_test.cpp	New unit tests for fork choice behaviors.
tests/unit/blockchain/CMakeLists.txt	Add fork_choice_test target.
DEPRECATED.md	Note naming convention differences from spec (comment-only).

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