[Jimbo4350]

Context

Fix decoding of Plutus data in Dijkstra required top-level guards by temporarily pinning cardano-ledger to the final commit of IntersectMBO/cardano-ledger#6189 (a2041c4bd73995fb4ab3b90db03fdf8ff464e104).

The ledger revision changes interfaces used by the released API, consensus, and CLI. Pin compatibility commits on remote dependency branches:

• cardano-api: srp/cardano-ledger-6189, commit 326a8f02df4ff1bb8a862aba23ed7e0cbe40a32c.
• ouroboros-consensus: srp/cardano-ledger-6189, commit 7ef5dc2474d42eeccc8244c9d2a5379ea2405df7.

Each branch contains the source changes and updated dependency bounds. The CLI uses ordinary SRPs with source hashes; no checkout-time substitutions or Nix patches are needed. Update the CLI's pool-state construction, ledger-state JSON encoder, guard tests, and minimum ledger versions, and include a Herald bugfix fragment. Bound overrides remain only for affected released dependencies.

How to trust this PR

Validated locally on Linux with GHC 9.12.4 and the existing local crypto-library configuration:

• cabal build all --enable-tests passed.
• CARDANO_CLI="$(cabal list-bin exe:cardano-cli)" cabal test all --enable-tests --test-show-details=direct passed: 821 golden tests and 115 CLI tests, including the sub-transaction guard tests.
• Fourmolu, HLint, Alejandra, Cabal Gild, and whitespace checks passed. These checks were run directly because the local pre-commit hook references a missing Nix interpreter.
• Verified the SRP source hashes with nix-prefetch-git and checked Nix syntax. A full Nix build and other platforms/compiler versions have not been tested locally.

These temporary source pins should be replaced when compatible dependency releases are available.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• Existing tests updated and run
• Self-reviewed the diff
• Changelog fragment added in .changes/