Add official Somnia RPC endpoints

[Goonzalox31]

Summary

• Adds the official Somnia mainnet RPC endpoint (chain ID 5031).
• Adds the official Somnia testnet RPC endpoint (chain ID 50312).
• Adds official browser and network-information documentation links.

Type of change

• Update data rows

Scope

• Networks affected: Somnia mainnet and testnet
• Categories affected: APIs

Links

• Official network information: https://docs.somnia.network/developer/network-info

Validation checklist

• I followed the Style Guide and Column Definitions.
• I personally opened and verified every new link added.
• I personally confirmed the provider support and every adjusted cell.
• This PR is not a blind AI-generated submission.

Optional

• Rewards address:
• Twitter (X) post link: