fix: hide native tokens on Tempo networks (testnet and mainnet) [WIP]

[khanti42]

Explanation

Tempo testnet (eip155:42431) and Tempo mainnet (eip155:4217) return arbitrary large numbers for native token balances via eth_getBalance. Showing these in the wallet would be misleading. This PR hides native tokens on those chains end-to-end: in AssetsController.getAssets, in balance fetching (AccountTrackerController and RPC balance fetcher), and in asset selectors so the UI never shows Tempo native tokens.

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