lean sample peer

[turuslan]

• secp256k1 compact signature of keccak hash for ENR.
• SamplePeer accepts ip

[Copilot]

Pull Request Overview

This PR implements Keccak hashing support and enhances secp256k1 signing capabilities to support Ethereum Name Record (ENR) operations. The main changes enable compact signature generation using keccak256 hashes instead of SHA-256.

Key Changes:

• Added Keccak-256 hash implementation for ENR compatibility
• Extended secp256k1 provider to support compact signatures with prehashed data
• Refactored SamplePeer to accept custom IP addresses and extract key generation logic

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/crypto/sha/keccak.cpp	Implements Keccak-256 hashing algorithm with incremental update and finalize methods
src/crypto/sha/CMakeLists.txt	Adds keccak.cpp to the build configuration
include/libp2p/crypto/sha/keccak.hpp	Declares Keccak class interface with hash operations
include/libp2p/crypto/secp256k1_types.hpp	Adds type definitions for compact signatures and prehashed data
include/libp2p/crypto/secp256k1_provider.hpp	Extends interface with signCompact and verifyCompact methods
include/libp2p/crypto/secp256k1_provider/secp256k1_provider_impl.hpp	Declares implementation of new signing methods and internal helper functions
src/crypto/secp256k1_provider/secp256k1_provider_impl.cpp	Refactors signing/verification to support both standard and compact signatures with prehashed input
include/libp2p/common/sample_peer.hpp	Refactors to extract keypair/port generation and adds IP address parameter support

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}