Add Rootstock support to MetaMask Account API

### What is this about?

### 🧩 Description
For the Rootstock community, it would be important to have Rootstock integrated into the MetaMask Account API:
- https://price.api.cx.metamask.io
- https://accounts.api.cx.metamask.io.

This integration would unlock the ability to list Rootstock-based tokens within MetaMask, improving visibility and accessibility for users and developers.

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### 💡 Why it matters
Adding Rootstock support would:

- Enable native token listing for the Rootstock ecosystem.
- Facilitate interoperability between dApps and wallets using the Account API.
- Strengthen MetaMask’s multi-chain reach by including a Bitcoin-native EVM network.

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### ✅ Expected outcome
- Rootstock (`chainId: 30`) added to the Account API.
- Rootstock tokens retrievable and displayable via MetaMask’s price API.
- Add Rootstock to the API

### Scenario

_No response_

### Design

_No response_

### Technical Details

_No response_

### Threat Modeling Framework

_No response_

### Acceptance Criteria

_No response_

### Stakeholder review needed before the work gets merged

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

### References

_No response_

Start by locating the MetaMask Account API and price API integration points referenced in the issue. Trace how supported chains and tokens are listed, then verify that chainId 30 and Rootstock token retrieval and display are covered when the integration is complete.

Written by the indexing model from the issue text.