Refactor X402Config to use network-keyed configuration for both EVM and SVM

[0x402ai]

Refactor X402Config to use network-keyed configuration for both EVM and SVM

• Replace flat SvmConfig with network-mapped types SvmConfig and EvmConfig (Partial<Record<Network, ...>>).
• Extend X402Config to expose svmConfig?: SvmConfig and evmConfig?: EvmConfig.
• Update all usages and tests to the new nested structure.
• API surface changes (applies to createSvmConnectedClient and other similar functions):
  • network: string → network: Network for stronger parameter constraints and improved IDE hints.
  • rename parameter config → x402Config (type unchanged).
• Commented out iotexTestnet in typescript/packages/x402/src/types/shared/evm/wallet.ts since it doesn’t exist in the supported networks.

Migration note: read RPC URLs from x402Config?.svmConfig?.[network]?.rpcUrl or x402Config?.evmConfig?.[network]?.rpcUrl.

Example:

const x402Config: X402Config = {
  svmConfig: { solana: { rpcUrl: "https://api.mainnet-beta.solana.com" } },
  evmConfig:  { base:   { rpcUrl: "https://mainnet.base.org" } },
};

Description

Tests

Checklist

• I have formatted and linted my code
• All new and existing tests pass
• My commits are signed (required for merge) -- you may need to rebase if you initially pushed unsigned commits

[cb-heimdall]

🟡 Heimdall Review Status

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[0x402ai]

Some files that I didn’t modify are reported by the formatter due to line ending (CRLF/LF) inconsistencies.
All modified files have passed the format check , lint check and the tests.
It might be better to address the cross-platform line ending differences in a separate commit and establish a consistent rule in the repository.