Add mfenx (chainId 177155) metadata path for custom-network recognition

[JROChub]

Requesting metadata-path recognition for mfenx custom network (chainId 177155).\n\nSubmitted chain metadata PR to chainid source: https://github.com/ethereum-lists/chains/pull/8087\n\nNetwork:\n- Name: mfenx\n- Chain ID: 177155 (0x2b403)\n- RPC: https://indexer.mfenx.com/rpc\n- Native currency: JULIAN\n- Metadata JSON: https://mfenx.com/.well-known/mfenx-network.json\n- Icon: https://mfenx.com/brand/mfenx_token_logo_inverse_512.png\n\nGoal: ensure MetaMask network metadata surfaces can resolve this chain once upstream chain data lands.

[JROChub]

Update: submitted ERC-20 token metadata/logo PR for MFENX to contract-metadata: https://github.com/MetaMask/contract-metadata/pull/1730\n\nChain metadata PR remains open at ethereum-lists/chains#8087.