feat: add aligned status tracking to MultichainAccountGroup

[gantunesr]

Explanation

Expose group alignment as aligned or missing-accounts so consumers can tell when a group is missing Ethereum, Solana, Bitcoin, or Tron accounts without calling isAligned() directly. Publish :multichainAccountGroupStatusChange when that status changes after updates.

Additionally, it protects group state mutations with a mutex and make init/update async, mirroring the wallet pattern. MultichainAccountWallet.init is now async to await group initialization.

References

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