fix(assets-controller): fetch metadata for balances missing assetsInfo

[salimtb]

DetectionMiddleware only queues brand-new assets, so already-tracked balances without metadata never got enriched and stayed invisible in clients.

Explanation

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

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Note

Low Risk
Scoped enrichment and network-list changes in the assets pipeline; no auth or breaking API changes, with regression coverage for the balance-only metadata path.

Overview
Token metadata enrichment now covers tokens that already appear in assetsBalance but lack assetsInfo (or an image), not only assets queued via detectedAssets. That closes a gap where tracked balances could stay invisible in clients because detection middleware only queues brand-new assets.

TokenDataSource middleware walks response.assetsBalance with the same skip rules as detection (existing image in response/state, staking contracts) and batches those asset IDs into the existing Tokens API v3 fetch.

Robinhood Chain (4663 / 0x1237) is added to SUPPORTED_NETWORKS_ACCOUNTS_API_V4 in @metamask/assets-controllers so balances and token detection use the Accounts API instead of RPC-only paths.

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