Remote ReadStateService

[idky137]

Opens the ReadStateService to remote use, as detailed in #9337.

• Closes feature: Remote ReadStateService. #9337

Motivation

Zebra’s ReadStateService currently only allows local access, limiting its integration with external tools and remote debugging. Enabling remote access would streamline workflows, simplify testing, and support scalable, decentralized deployments—fostering a more modular and community-friendly Zcash ecosystem.

Solution

1. Add Serde serialization to ReadRequest and ReadResponse.

• Deserialises NetworkKind into default Network type to avoid serialising whole Network.
• Implements Display and FromStr for TransactionLocation and OutputLocation and uses for serialisation.
• built on top of changes in Add Serde serialization to structs in zcash_history. zcash/librustzcash#1745.

2. Add remote_state_call RPC to Zebra's JsonRPC server.

• Adds new RemoteStateRpc trait to methods.rs and implements for RpcIml.
• Adds new RPC to server spawn method.

3. Add RemoteStateService as endpoint to new remote functionality.

• Adds RemoteStateService struct to service.rs.
• Implements tower::Service for equivalent functionality to the ReasdStateService.

NOTE: This feature has been added under the "remote_read_state_service" feature flag, this could be removed if this functionality should be enabled by default.

NOTE 2: This feature is now ready for review but is built on zcash/librustzcash#1745. For that reason I have left as draft until that PR lands.

Tests

Currently no new tests have been added, this is largely due to struggling to work out where / how tests should be added for this feature. I am happy to add any tests that are required.

Currently this code is tested in Zaino in the following PR: zingolabs/zaino#247.

Specifications & References

Follow-up Work

PR Checklist

• The PR name is suitable for the release notes.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.
• If the PR shouldn't be in the release notes, it has the
  C-exclude-from-changelog label.