feat(rpc): implement a live HTTP transport over the official client #1

Problem

devkit-rpc defines a Transport trait and a mock, but there is no transport that actually talks to a Stellar RPC node.

Why this matters

Without a live transport the toolkit cannot perform real RPC-based workflows, which is a core part of the product.

Context

The official stellar-rpc-client crate (28.0.0-rc.1) exists; integrate it rather than writing a JSON-RPC client from scratch.

Scope

• Implement a Transport backed by stellar-rpc-client, behind a non-default feature if it adds heavy dependencies.

• Map transport errors into DevkitError without panicking.

Out of scope

• New RPC methods beyond those already modeled.

• Authentication or paid-provider specific behavior.

Technical guidance

• Study the stellar-rpc-client API before implementing; adapt it to the Transport trait.

• Keep the mock transport the default in tests; the live transport must be opt-in.

Relevant modules/files

• crates/devkit-rpc/src/lib.rs

• crates/devkit-rpc/Cargo.toml

Acceptance criteria

• A live transport can call getHealth against a configured endpoint

• Errors are structured and non-panicking

Tests required

• Unit tests with a recorded/loopback server where feasible

• A test asserting the transport is not used by default

Security considerations

The transport must only use validated Endpoints and must not log credentials.

Performance considerations

Reuse a single connection pool where the client allows it.

Documentation requirements

Document supported methods and the fact that live RPC is opt-in.

Dependencies

None.

Definition of done

Merged with tests passing and CI green.

Complexity recommendation

difficulty/high

Contribution guidelines

• Assignment required before starting. Request assignment on this issue; do not open a pull request until a maintainer has assigned you.

• Your pull request must include Closes #1.

• Run the local gate before opening the PR:

  cargo fmt --all -- --check
  cargo clippy --all-targets --all-features -- -D warnings
  cargo test --all
  

• Example commit message: feat(rpc): implement a live HTTP transport over the official client

• Suggested timeframe: complete within the active Wave cycle.

• Complexity is tagged with a difficulty/* label. Drips determines the applicable points and budget through its own system.

• See docs/WAVE.md and CONTRIBUTING.md.