Cardano Updates

Co-authored-by: Alexey Kuleshevich <[email protected]>

Rename failsToCompile -> caseListTwice (it compiles now).
Update golden files affected by the BuiltinData second constructor.

GHC's simplifier unconditionally unwraps single-constructor types.
For `data BuiltinData = BuiltinData ~Data`, this exposes `Data` in
join point type signatures. The plugin with BuiltinCasing then tries
to compile Data as a regular ADT, walks B ByteString -> BS Addr#,
and crashes.

Fix: add a second (unreachable) constructor to BuiltinData so GHC
cannot apply case-of-single-constructor. A COMPLETE pragma ensures
existing pattern matches remain exhaustive without warnings.

  Adds withSQLiteEventStore that manages the writer thread lifecycle
  automatically — link surfaces crashes, finally ensures flush + cancel
  on exit. Callers no longer need to manage cleanup manually.

so that it gets applied only if transaction is valid, and at both top
and sub level

Address Javier's review comment: reword the sentence about valid
prefixes to make it clearer that it is the valid prefix (not the
invalid block itself) that might be part of a valid chain from
another peer.

First-elaboration explanation of the consensus protocol abstraction,
covering chain selection, header validation, the security parameter k,
and the ConsensusProtocol class with its associated types and methods.

This is a first iteration — future work includes:
- Concrete protocols section (PBFT, TPraos, Praos characterizations)
- Block forging section (leadership check, self-adoption)
- Chain order details (PraosChainSelectView, RestrictedVRFTiebreaker)
- Formal invariants (prefer extension, never shrink)
- Blueprint references and Haddock reverse links
- "Go deeper" section once deeper pages exist
- Cross-era forecasting details

Also adds glossary entries for "extended ledger state" and
"immutable tip".