Description

Adds the FetchBlock SyncService method to the node's embedded gRPC server, backed by in-process node kernel access (ADR-019).

This PR integrates and tests IntersectMBO/cardano-api#1247, which implements the UTxO RPC transaction mapping that FetchBlock serves.

Node changes:

• Cardano.Node.Run now publishes a NodeKernelAccess handle to the RPC server through an IORef once the node kernel starts, so FetchBlock reads blocks directly from ChainDB instead of going over a Node-to-Client connection.
• A new RpcUnsupportedBlockType startup message reports when node kernel access is unavailable for the running block type.
• SyncService tracing: TraceRpcSync log rendering (FetchBlock request spans, block-not-found, forker errors, kernel access unavailable) and an rpc.request.SyncService.FetchBlock prometheus counter.

Test changes (cardano-testnet-test):

• New E2E test Cardano.Testnet.Test.Rpc.FetchBlock: submits a payment transaction and a native-script minting transaction over gRPC, locates their blocks, fetches them via FetchBlock and asserts the mapped transaction fields (hash, fee, inputs, outputs, validity, mint, witness set contents) against the submitted values. Also covers the error paths: NOT_FOUND for an unknown block hash and INVALID_ARGUMENT for a malformed one.
• Rpc.Query now decodes rational protocol parameters with utxoRpcRationalNumberToRational instead of comparing injected encodings.
• TestnetRuntime.testnetNodes is now NonEmpty, with small cleanups in the other RPC test modules.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Running tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-9.6 and ghc-9.12
• Self-reviewed the diff

Note on CI

If your PR is from a fork, the necessary CI jobs won't trigger automatically for security reasons.
You will need to get someone with write privileges. Please contact IOG node developers to do this
for you.