Switch proto-lens SRP from carbolymer fork to google upstream master

[carbolymer]

Changelog

- description: |
    Switch proto-lens SRP from carbolymer fork to google upstream master
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
   - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...
# uncomment at least one main project this PR is associated with
  projects:
  # - cardano-api
  # - cardano-api-gen
   - cardano-rpc
  # - cardano-wasm

Context

The carbolymer fork of proto-lens was used as a temporary workaround for GHC 9.12 support. Now that the upstream fix has been merged (google/proto-lens#519), we can switch the source-repository-package to point directly at google/proto-lens master.

The SRP is now conditional on impl(ghc >= 9.12) so it only applies where needed.

How to trust this PR

• cabal.project: SRP switched from carbolymer/proto-lens to google/proto-lens at the merge commit of #519, gated behind impl(ghc >= 9.12)
• flake.nix: Nix fetch updated to match, with symlink fixing and simplified package overrides via lib.genAttrs

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[Copilot]

Pull request overview

Updates the proto-lens source-repository-package (SRP) pin to use the upstream google/proto-lens repo (instead of the carbolymer fork) and wires Nix to fetch the repo with submodules while fixing problematic symlinks.

Changes:

• Pin proto-lens SRP to an upstream google/proto-lens commit for GHC ≥ 9.12.
• Add a Nix fetch + “symlink fixing” derivation for proto-lens (including submodules).
• Simplify Nix package source overrides by generating overrides for a set of proto-lens subpackages.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
flake.nix	Fetch upstream proto-lens with submodules, patch symlinked paths, and override build sources accordingly
cabal.project	Switch SRP from carbolymer/proto-lens to google/proto-lens for GHC ≥ 9.12

[Jimbo4350]

🚀 🚀 🚀

[Copilot]

@carbolymer I've opened a new pull request, #1145, to work on those changes. Once the pull request is ready, I'll request review from you.