Cardano Updates

ForkTreeState tracks per-host current tips and a global
parent map. Edges are recorded on AddedToCurrentChain
(producer's own extension always captures the true parent);
SwitchedToAFork only updates the host's tip without
recording an edge.

clusterForkDepth = max(tip.chainLength) - commonAncestor.chainLength,
where commonAncestor walks each host's ancestry back (capped
at maxDepth) and intersects to find the deepest shared block.

8 hspec unit tests cover: empty state, sequential extension,
agreement, 1-block fork, root-only common ancestor, deep 5-block
divergence, setTip without edge, depth-cap truncation.

Part of #119 — pure algebra commit; wiring + persistence in
follow-up commits on this branch.

Adds a SwitchedToAFork constructor to LogMessageData. Previously
these events fell through to OtherLogMessageData. Required for the
ForkTree probe (#119) to track per-host current-tip transitions
that bypass sequential extension.

Tests still green; golden output unchanged because no existing
rule matches SwitchedToAFork.

Update 11.0 to 11.0.0 for CI
Match repo config files with iohkNix for CI
Update peer-snapshots and useLedgerAfterSlot for each environment