feat(keyring-eth-money): add money account keyring based on hd-key-ring

[Jwhiles]

Implements a new keyring to support MUSD-386

Examples

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Note

Medium Risk
Introduces a new keyring package and extends the public KeyringType enum, which may affect downstream consumers and account derivation behavior if integrated incorrectly.

Overview
Adds a new @metamask/eth-money-keyring package that extends @metamask/eth-hd-keyring with a dedicated type ("Money Keyring"), a fixed derivation path (m/44'/4392018'/0'/0), and enforced single-account behavior (overridden deserialize/addAccounts).

Updates @metamask/keyring-api to include KeyringType.Money (plus type-level tests and changelog), and wires the new package into repo tooling/docs (README module list/graph, root tsconfig.build.json, PR-title scope allowlist, and yarn.lock).

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[danroc]

Should we remove the ability to add accounts directly? We could override addAccounts to only allow 1 account to be added.

Yes, if this is what the product expects, we should enforce it. Otherwise, we might mistakenly create more than one account and end up dealing with this kind of hard-to-solve bug.

[danroc]

Calling it Cash Account for a keyring is a bit confusing because it overlaps with the concept of account. Using just Cash might be clearer.

WDYT @gantunesr, @ccharly ?

[ccharly]

Calling it Cash Account for a keyring is a bit confusing because it overlaps with the concept of account. Using just Cash might be clearer.

WDYT @gantunesr, @ccharly ?

I think you're right yep!

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[Jwhiles]

@metamaskbot publish-preview

[github-actions]

Preview builds have been published. See these instructions (from the core monorepo) for more information about preview builds.

Expand for full list of packages and versions.

{
  "@metamask-previews/account-api": "1.0.0-25e4b24",
  "@metamask-previews/hw-wallet-sdk": "0.5.0-25e4b24",
  "@metamask-previews/keyring-api": "21.5.0-25e4b24",
  "@metamask-previews/eth-cash-keyring": "0.0.0-25e4b24",
  "@metamask-previews/eth-hd-keyring": "13.1.0-25e4b24",
  "@metamask-previews/eth-ledger-bridge-keyring": "11.3.0-25e4b24",
  "@metamask-previews/eth-qr-keyring": "1.1.0-25e4b24",
  "@metamask-previews/eth-simple-keyring": "11.0.0-25e4b24",
  "@metamask-previews/eth-trezor-keyring": "9.0.0-25e4b24",
  "@metamask-previews/keyring-internal-api": "10.0.0-25e4b24",
  "@metamask-previews/keyring-internal-snap-client": "9.0.0-25e4b24",
  "@metamask-previews/eth-snap-keyring": "19.0.0-25e4b24",
  "@metamask-previews/keyring-snap-client": "8.2.0-25e4b24",
  "@metamask-previews/keyring-snap-sdk": "7.2.1-25e4b24",
  "@metamask-previews/keyring-utils": "3.2.0-25e4b24"
}

[ccharly]

LGTM, we'll follow-up with another PR to re-specialize serialize and deserialize so it matches the keyring's semantic even more (see https://github.com/MetaMask/accounts/pull/472/files#r2959166319)