wasm: export coin checks, forfeits and releases for Arca

[GracedEternalKingCabbageMan]

A page could verify a leaf taken from a round, but not a coin received out of round, and it could not build what it signs when it gives a leaf up: the forfeit and the release. The native kit already has these. The bindings now carry them on ArkVerifier, each at the median time the call names.

Coins.

• verifyCoin(coin, rounds, ownerKey, ownerNonce, now, chain?) checks a coin record against the rounds and boards its lineage came from, for the wallet's key and nonce.
• The lineage check needs the chain, which a page can only reach asynchronously. So coinLineage(coin, rounds, now) first lists the lineage scripts and boards to look up, and verifyCoin then takes what the chain source found ({ paid, spent }).
• A coin with a lineage script paid or a board spent is refused, kind on_chain. Without chain, the verdict says the coin rests on the operator's rule.

Forfeits and releases. forfeitRefresh, forfeitOffboard, releaseRefresh and releaseOffboard wrap the native builders, so h and M come from the leaf and round the wallet validated. Each returns the message in the form signCsfs takes, with its digest, and gives M in display hex.

Byte-order vector. It gains a release (M in display hex at the edge, internal order in the message, taken from the Arca signer vectors) and a received coin (its asset in display hex as the kit gives it, internal order in the record). Both are checked in Rust and through the bindings.

Tested:

• ark_records.js:
  • every received coin in the transfer vectors verifies (7 coins; 2 of them rest on a board);
  • a paid lineage script and a spent board are refused with on_chain;
  • the record promising one leaf twice is refused with salt, another key or nonce with owner, and a missing board transaction with round;
  • { payd: [] } is refused: unknown field \payd``.
• ark_regtest:
  • the node mines a round that pays the wallet a new leaf, an offboard output and the operator's connector at output 2;
  • the four digests built through the bindings equal the native ones, and M is that round's connector asset;
  • the four signatures signCsfs makes with the old leaves' keys verify natively;
  • a release signed for this round does not verify for another round's M;
  • refused: a connector at the wrong output; the new or old leaf checked against the wrong round; another nonce; an unknown offboard field; a ceiling below the margin.
• arca_signers.js, arca_regtest.py (Tests successful), lwk_signer (26 tests; 27 with ark) and lwk_wollet ark:: (29) all pass.