Cardano Updates

Co-authored-by: Pablo Lamela <[email protected]>

NetworkTopology was moved to ouroboros-netowork and refactored, which causes the
following changes in cardano-testnet:
- `createTestnetEnv` now creates a concrete topology, instead of an abstract one
- `createTestnetEnv` now allocates random ports to nodes and writes them
  both to the concrete topology file and the to the nodes config directories
- `cardanoTestnet` now does not generate the ports and instead reads the ones
assigned by `createTestnetEnv` from disk

New --rollback-rate flag for the serve command generates random chain
rollbacks (depth 1-3) on an independent Poisson schedule. The ChainSync
server detects when a client's read pointer is invalidated by a rollback
and sends MsgRollBackward. Default rate is 0 (no rollbacks).

Example: --block-rate 1.0 --rollback-rate 0.1

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

The server-side Request/Response enums were 1:1 mappings of Message
variants, and receive_request()/send_response() were pure conversion
boilerplate. The Runner already enforces agency and state transitions,
so these types added no safety.

Server code now uses runner.recv()/runner.send() with Message directly,
matching the simplicity of the protocol framework design.

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

Add symmetric Request/Response enum pairs with receive_request() and
send_response() functions for ChainSync, BlockFetch, and KeepAlive
protocols. Add accept_and_handshake() server connection helper.

New `serve` CLI command runs a fake Cardano node that generates blocks
on a Poisson schedule (configurable rate), serves ChainSync/BlockFetch/
KeepAlive to connecting clients. Live-tested with the `follow` command.

Also fix all pre-existing clippy warnings (matches! macro, io::Error::other,
map key iteration).

109 tests, zero clippy warnings.

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

  The old dumpTrace used say which in IO context dumps the entire IOSim
  trace (potentially thousands of JSON lines) to stdout on test failure.
  With slow-network tests generating much larger traces, this was very
  noisy. Now the trace is written to a temp file and only the path is
  printed.

Signed-off-by: Sasha Bogicevic <[email protected]>

Export reusable validations to future eras and update the BBODY signal.

Update version dependencies for core and shelley packages.

* Export reusable validations to future eras and update the BBODY signal.
* Move isOverlaySlot calculation into incrBlock.

Without KeepAlive (protocol ID 8), the peer drops idle connections after
~60-90s. Add KeepAlive protocol implementation (state machine, CBOR codec,
cookie validation) and run it as a background task in the follow command,
pinging every 20s. Live-tested: connection now stays alive indefinitely.

109 tests total (11 new for KeepAlive).

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

token metadata for Bheem token