feat: use @metamask/superstruct exactOptional support

[ccharly]

Start using @metamask/superstruct object and exactOptional instead of our local implementation.

---

Note

Medium Risk
Breaking public API on keyring-utils and wide import changes affect every runtime schema in the monorepo; validation semantics should match @metamask/superstruct 3.3.0 but downstream consumers must update imports.

Overview
Breaking: @metamask/keyring-utils no longer exports object, exactOptional, or type. Callers across keyring-api, keyring-utils, snap packages, and related workspaces now import those helpers directly from @metamask/superstruct, with dependencies bumped to ^3.3.0.

ESLint no-restricted-imports blocks raw superstruct and the removed symbols from @metamask/keyring-utils, steering new code to @metamask/superstruct. Local implementations and their unit tests were deleted; strictMask and selectiveUnion remain in keyring-utils. Type-level exactOptional behavior is covered by retained tsd tests, and KeyringAccountOptionsStruct gains a case asserting entropy: null fails validation.

packages/keyring-api/src/eth/types.ts now imports EthScope from ./constants instead of the package barrel.

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[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	@​metamask/​superstruct@​3.2.1 ⏵ 3.3.0

View full report

[ccharly]

Using no-changelog since most of those changes are internals.

I did add a changelog entry for keyring-utils though!