[Peras 63] Add PerasState to ExtLedgerState

[agustinmista]

This PR:

• Adds PerasState to ExtLedgerState and its ticked form, tracking the Peras epoch-context resolver and latest on-chain Peras certificate round.
• Updates ticking to advance the Peras resolver (block application now detects Peras certificates and monotonically updates the cached latest certificate round).
• Adds Ouroboros.Consensus.Peras.Voting.Mock, providing mock voting-committee input derived from the mock ledger’s pool-stake distribution for Peras-enabled test blocks.
• Adds a handle for reading the resolver from the current ledger state (mkPerasEpochContextResolverHandle).
• Updates all production, mock, and test node initialisation paths to construct Peras state.
• Extends ExtLedgerState CBOR/disk serialisation to persist Peras state (backwards compatible).
• Threads the required Peras, epoch-context, and hard-fork constraints through LedgerDB, ChainDB, node runtime, hard-fork combinators, DB analyser, benchmarks, and test infrastructure.
• Updates ChainDB models/state-machine tests and test blocks, including mock voting-committee support and supporting instances (Show, Eq, NoThunks, CBOR, etc.).
• Regenerates the ten ExtLedgerState golden files.

Please note that some of the new instances required here are placeholders to be updated in tandem with getting rid of the degenerate BlockSupportsPeras instance.

Moreover, the bulk of the changes happen in a handful of files, the rest being mostly plumbing. Enabling Hide whitespace in the diff view helps a bit :)