[FEATURE] Implement Viem-based custom client for ADR-0003: Typed Transaction 0x76 Sponsorship

[randygrok]

Is your feature request related to a problem? Please describe.

Currently, there is no user-facing client implementation to construct, sponsor, and broadcast EIP-2718 typed transactions of type 0x76 (as proposed in ADR-0003: Typed Transactions for Sponsorship and Batch Calls). Without a reference client, developers and integrators cannot easily generate or sign these sponsored transactions, making the sponsorship mechanism and batch calls in ADR-0003 hard to adopt and test.

Describe the solution you'd like

Build a custom client for the EvNode 0x76 transaction type, following the architecture and recommendations in ADR-0003 (docs/adr/ADR-0003-typed-transactions-sponsorship.md):

• Use the Viem JavaScript/TypeScript library and its custom client pattern.
• The client must:
  • Construct 0x76 typed transactions according to the spec (encoding, two signatures, batch call support).
  • Support both executor and sponsor signing flows (as described in the "Sponsorship Flow" of the ADR).
  • Produce and broadcast valid 0x76 transactions, properly RLP-encoded as specified.
  • Validate signatures and expose utility methods (recover executor/sponsor, check ready-to-broadcast, etc.)
  • Provide TypeScript typings and examples for usage.
• Follow the reference workflow and considerations in the ADR and ensure compatibility with the node-side implementation.

Additional context

• See docs/adr/ADR-0003-typed-transactions-sponsorship.md for encoding, signing, and architecture details.