fix: fix stale reference for multichain assets state

[sahar-fehri]

Explanation

PR fixes wrong rates for non-evm chains.

References

• Fixes #12345

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

MultichainAssetsRatesController now fetches accountsAssets from state on demand instead of caching, fixing stale rates; adds targeted tests and updates changelog.

• Assets Controllers:
  • MultichainAssetsRatesController
    • Remove cached #accountsAssets; #getAssetsForAccount now calls MultichainAssetsController:getState each time to get fresh accountsAssets.
    • Minor typing/return annotations and async-safe event subscriptions.
• Tests:
  • Add "dynamic asset fetching" test ensuring rates are fetched for assets added post‑init.
  • Adjust setupController to return typed helpers; import CaipAssetType.
• Changelog:
  • Document fix for stale accountsAssets causing incorrect non‑EVM conversion rates when currency changes.

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