Align aggchain gRPC public_values compat codec with SP1/prover encoding

[Freyskeyd]

Summary

agglayer-interop-grpc-types currently serializes and deserializes aggchain public_values in gRPC v1 compat using plain workspace bincode.

Agglayer and the provers repo indicate that aggchain public_values should use the SP1/prover codec semantics instead, specifically the sp1v4() bincode configuration.

This mismatch blocks Agglayer from safely relying on interop's TryFrom<v1::AggchainProof> / TryFrom<v1::AggchainData> conversions without reimplementing local parsing.

Evidence

• In provers, aggchain proof public values are encoded/decoded with bincode::sp1v4():
  • crates/aggkit-prover/src/rpc.rs
  • crates/aggchain-proof-builder/src/lib.rs
• In agglayer-interop-grpc-types, compat currently uses plain bincode in:
  • crates/agglayer-interop-grpc-types/src/compat/v1/aggchain_data/v1_to_types.rs
  • crates/agglayer-interop-grpc-types/src/compat/v1/aggchain_data/types_to_v1.rs
• The byte-level mismatch shows up in origin_network endianness inside AggchainProofPublicValues.

Proposed Change

• Update gRPC compat public_values parsing and encoding in agglayer-interop-grpc-types to use the SP1/prover codec configuration rather than plain default bincode.
• Add regression tests that pin the expected wire bytes for both:
  • generic aggchain proof public_values
  • bare aggchain proof public_values

Why It Matters

Once interop gRPC compat uses the same codec as the prover/public proof producer, Agglayer can rely on interop structural conversions for aggchain data instead of maintaining duplicated parsing logic locally.

Acceptance Criteria

• public_values gRPC compat encode/decode uses the SP1/prover-compatible codec.
• Existing or new tests verify the expected byte order for origin_network and other fields.
• Agglayer can consume interop conversions without public_values wire-format regressions.