feat(snap-account-service): add migration logic + keyring v2 support

[ccharly]

Explanation

Add migration logic to migrate from the legacy Snap keyring to the new architecture with 1 Snap keyring v2 per Snaps.

Also enhance :ensureReady so consumers can safely call :withKeyringV2 to get the associated Snap keyring v2 instance before using it.

References

N/A

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

High Risk
High risk because it changes Snap account/keyring lifecycle (migration, auto keyring creation, and message routing) which directly affects account persistence and Snap-driven account operations.

Overview
Implements a legacy Snap keyring → per-Snap v2 keyring migration in SnapAccountService (migrate), designed to be concurrent-safe, retried on failure, and automatically invoked by ensureReady.

Updates ensureReady to run migration first and then atomically create the v2 keyring for a Snap if missing before waiting on platform readiness; handleKeyringSnapMessage is switched to forward messages via KeyringController:withKeyringV2 (with special-casing for GetSelectedAccounts and auto-create on AccountCreated).

In multichain-account-service, Snap-based providers drop KeyringController:withKeyring usage entirely: BaseBip44AccountProvider removes the v1 helper, SnapAccountProvider now targets eth-snap-keyring/v2 APIs (including deleteAccount), and BTC/SOL/TRX/Snap provider tests are updated accordingly; changelogs and dependencies are bumped to reflect these breaking API shifts.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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Migration breaks proactive selected account forwarding to snaps

Medium Severity

The #migrate() method removes the legacy snap keyring via controller.removeKeyring(...), but #forwardSelectedAccounts — which is wired to fire on selectedAccountGroupChange, unlock, and account group lifecycle events — still calls getLegacySnapKeyring(). That method is get-or-create, so after migration it silently spins up a new, empty legacy keyring and calls setSelectedAccounts on it. Since no snaps are connected to this empty keyring, proactive selected-account notifications stop reaching any snap after migration completes.

Additional Locations (1)

• packages/snap-account-service/src/SnapAccountService.ts#L598-L617

 

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