Cardano Updates

# Conflicts:
#	ouroboros/chainsync.go
#	ouroboros/chainsync_test.go

Transactions with isValid=false are consensus-valid on Cardano: the
block producer determined the Plutus script failure, and collateral
is consumed instead of regular inputs. The gouroboros Transaction
interface already handles this via Consumed()/Produced() which return
the correct collateral-based UTxO sets.

Previously dingo ran ValidateTxFunc on all transactions regardless of
the isValid flag, causing phase-1 UTxO validation rules to reject the
block (e.g. bad inputs, value not conserved) because they checked the
regular inputs which were never consumed on-chain.

Gate the ValidateTxFunc call on tx.IsValid() so phase-2 failed TXs
are recorded with their collateral effects without triggering spurious
block validation failures.

Signed-off-by: wcatz <[email protected]>

Revert connection-recycle-on-resync (43306a9) and keep-idle-ownership
(0e1b479) to restore same-connection chainsync restart and idle header
owner release.

Change the plateau detector to publish ChainsyncResyncEvent instead of
ConnectionRecycleRequestedEvent so it restarts the chainsync client on
the same TCP connection rather than killing it. The old approach caused
a race where the replacement connection's lookup entry was destroyed by
the previous connection's deferred keep-alive cleanup, permanently
killing the header pipeline.

Convert the genesis hash mismatch after mithril bootstrap from a hard
error to a warning log so dingo can start cleanly on a mithril-seeded
PVC.

Signed-off-by: wcatz <[email protected]>

Add cabal-gild as part of the pre-commit hook in our Nix devShell.