Release/0.4.0

[programmaman]

Release v0.4.0

1. Remove dependency on ethers
2. Add ethers and viem adapters
3. update ci
4. Refactor client payment execution, proof resolution, policy handling, and payment error normalization.
5. Refactor server authorization, verification, settlement, consumption, refund, and dispute flows.
6. Improve settlement reference caching, historical block verification, and settlement-boundary handling.
7. Simplify Once() payment consumption and prevent duplicate provider-specific error decoding.
8. Add Ethers and Viem adapter unit-test coverage, including nonce-conflict recovery.
9. Update build, test, package, CI, and npm publish workflows.
10. Update package dependencies to @rakelabs/dpayments-sdk@0.2.1.