feat(statics): add MegaETH testnet ERC20 token support

[manojkumar138]

Description

Add MegaETH testnet ERC20 token support and fix network configuration issues.

The existing MegaETH network configuration had incorrect chain ID and swapped explorer URLs. This PR fixes those issues and adds a test token for integration testing.

Changes:

• Fix MegaETH testnet chain ID from 6342 to 6343 (verified via RPC call)
• Fix mainnet explorer URL from megaexplorer.xyz to megaeth.blockscout.com
• Fix testnet explorer URL from megaeth.blockscout.com to megaexplorer.xyz
• Add tmegaeth:tmt test token for integration testing
• Update chain ID mapping in map.ts

Test Token Details:

Property	Value
Symbol	tmegaeth:tmt
Name	Test Mintable Token
Contract	0x9abf1ca968783ba2ad3a75b6b7b2beece80a4fc2
Decimals	6
Network	MegaETH Testnet (Chain ID: 6343)
Explorer	https://www.megaexplorer.xyz/address/0x9aBF1Ca968783Ba2aD3a75B6B7B2BeEcE80a4FC2

Issue Number

Ticket: WIN-8346

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

1. Chain ID Verification: Verified correct testnet chain ID via RPC - Response: 0x18c7 = 6343 in decimal

2. Token Deployment: Deployed test ERC20 token on MegaETH testnet using coins-sandbox/eth/mint-testnet-erc20-tokens and verified minting functionality works.

3. Local Build & Tests: yarn workspace @bitgo/statics build and yarn workspace @bitgo/statics test both pass successfully.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My code compiles correctly for both Node and Browser environments
• I have commented my code, particularly in hard-to-understand areas
• My commits follow Conventional Commits and I have properly described any BREAKING CHANGES
• The ticket or github issue was included in the commit message as a reference
• I have made corresponding changes to the documentation and on any new/updated functions and/or methods
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[manojkumar138]

The audit failure is a pre-existing tar vulnerability (GHSA-8qq5-rm4j-mr97) that also exists on master. This is unrelated to my changes which only modify static token configurations. Can this check be bypassed for this PR?