Cardano Updates

Add golden tests for the rest of the query result types

This commit introduces a general hierarchy for common era testing

test(halo2_ivc): add Layer C1 in-circuit verification tests

Signed-off-by: Eric Torreborre <[email protected]>

bump scalus

Adds two modules to con-rs:

- `types::Point` (with Display + minicbor Encode/Decode codec).  Both
  consumers must agree on the on-wire encoding of a chain point, so the
  codec lives with the type.  con-rs picks up `minicbor` as a dep.
- `chain_tree` (`ChainTree`, `ChainTreeEntry`, `is_better_tip`,
  `ChainNode`): the fork-aware tree of block headers used by Praos
  longest-chain selection.  Lifted verbatim; HashMap iterations are
  sort-stabilized at the public API boundary, so internal collection
  choice doesn't leak determinism.  Adds `Default` impl and `is_empty`
  to satisfy clippy.

Net-core now depends on con-rs and re-exports `Point` via `pub use
con_rs::Point`, so all callers continue to import from
`net_core::types`.  Net-core's `Tip`, `MAX_POINTS`, `decode_points` /
`encode_points`, and the existing tests stay where they are — they're
wire-protocol concerns.

Net-node's `chain_tree.rs` is deleted; imports in telemetry, consensus
mod, and the praos sub-layer are rewritten to `con_rs::chain_tree::*`.

Verified: 57 con-rs tests pass (was 42 — +4 Point tests, +15 chain_tree
tests now run in con-rs), 529 net-rs workspace tests pass (was 544 —
the 15 chain_tree tests moved out), cargo clippy --all-targets shows 11
warnings in net-rs (baseline) and 0 in con-rs.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

Aligns PeerChain with Haskell's AnchoredFragment pattern: the
ChainSync intersection point is stored as an explicit anchor on
each peer's candidate chain. When select_chain_once's walk through
PeerChain entries fails to find a common ancestor (narrow window
after reconnection), the anchor provides a guaranteed fallback.

Changes:
- Forward NetworkEvent::IntersectionFound from coordinator to
  consensus (previously swallowed at the coordinator level)
- Add PeerChainAnchor struct and anchor field to PeerChain, set
  from IntersectionFound, persists through rollbacks
- Add anchor fallback in select_chain_once after the walk and
  prev_hash fallback both fail
- Detect gap between anchor and oldest PeerChain entry; thread
  anchor_point through WaitingForBlocks to issue_fetch so the
  fetch range starts from the anchor, filling the gap via
  BlockFetch

Three new tests: anchor_set_on_intersection_found,
anchor_used_as_fallback_ancestor, anchor_ignored_when_walk_succeeds.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>