feat: Implement ERC-2771

[boris]

This pull request introduces support for meta-transactions (ERC-2771) in the ClaimCLPc contract, updates deployment documentation with new contract addresses and flow explanations, and enhances the Makefile with new claim and meta-transaction commands. The most important changes are grouped below:

Smart contract: ERC-2771 meta-transaction support and refactoring

• Added trustedForwarder support in ClaimCLPc, including storage, setter (setTrustedForwarder), getter (isTrustedForwarder), and an internal _msgSender() that extracts the original sender from calldata if called via the trusted forwarder. This enables meta-transaction compatibility. [1] [2] [3]
• Refactored admin checks and claim logic to use _msgSender() for proper sender resolution (including meta-tx), and added an event for forwarder updates. [1] [2] [3]

Makefile: Claim and meta-transaction operations

• Added new Makefile targets for claim operations (check-claim, claim-direct, grant-claim-minter, etc.) and meta-transaction configuration (set-forwarder, check-forwarder, etc.), supporting easier contract interaction and admin tasks.
• Introduced new environment variables in the Makefile for MINTER, FORWARDER, and USER_PK to support these new operations.

Documentation: Deployment and usage updates

• Updated contract addresses for ClaimCLPc and added the new Forwarder address across deployment and smoke-test documentation, ensuring all references are current. [1] [2] [3]
• Expanded deployment docs with a detailed step-by-step explanation of the claim mint flow, checks for claim eligibility, and instructions for using meta-transactions with the trusted forwarder. Also added commands for checking supply and minting limits.

These changes collectively enable gasless claims via meta-transactions, improve contract maintainability, and make it easier for developers and admins to interact with and verify the system.