Introduce accounts/v0 namespace

[qnikst]

No description provided.

[Copilot]

Pull request overview

Adds support for the new accounts/v0 SCLS namespace by introducing its CDDL schema, registering it as a known namespace, and updating reference/CIP wiring so conformance checks can include it.

Changes:

• Add Cardano.SCLS.Namespace.Accounts CDDL schema and register accounts/v0 in Cardano.SCLS.CDDL (including key size).
• Extend reference CDDL loading list to include accounts_v0.cddl.
• Update Nix/CI pins to a CIPs revision/branch that contains the new accounts_v0.cddl.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
scls-cardano/testlib/Cardano/SCLS/Testlib.hs	Adds accounts/v0 to the “test all namespaces” constraint set.
scls-cardano/test/Reference.hs	Includes accounts/v0 reference CDDL filename in allReferenceCDDLs.
scls-cardano/scls-cardano.cabal	Adds the Accounts namespace module to the library build.
scls-cardano/cddl-src/Cardano/SCLS/Namespace/Accounts.hs	Introduces the Accounts namespace CDDL rules (record entry + supporting types).
scls-cardano/cddl-src/Cardano/SCLS/Common.hs	Adds word64_non_zero helper rule.
scls-cardano/cddl-src/Cardano/SCLS/CDDL.hs	Registers accounts/v0 spec and namespace key size; adds to known namespaces.
flake.nix	Switches CIPs input to the accounts ref.
flake.lock	Updates pinned CIPs revision/hash accordingly.
.github/workflows/haskell-ci.yml	Updates the checked-out CIPs commit used to provide reference CDDL.

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[qnikst]

After trying to integrate with cardano-ledger I realised that I've used spec types for DState, so I have to update that to use real data.

[joaosreis]

Done in #288