docs: add ERC-20 token bridge guide

[SilasZhr]

Summary

• Adds docs/dev/bridge-erc20.md — a step-by-step developer guide for bridging ERC-20 tokens from Ethereum to MegaETH using the OP Stack Standard Bridge
• Covers: deploy L1 token, register L2 counterpart via OptimismMintableERC20Factory, approve bridge, call bridgeERC20, verify L2 balance
• Includes contract addresses for both mainnet and Sepolia testnet in a {% tabs %} block
• Updates docs/SUMMARY.md to list the new page
• Adds a cross-link from docs/dev/overview.md's canonical bridge section

Based on the completed implementation in ~/workspace/bridge.

[claude]

Two blocking issues in the code samples — the rest looks good.

Blocking

1. Broken bash line continuations (inline comment on line 67) — \ followed by spaces and # comment breaks line continuation in all three cast send blocks (steps 2, 3, and 4). The commands won't run as written. Fix: move inline explanations to prose above each block.

2. Invalid event topic hash (inline comment on line 78) — 0x52fe89dd5930f343d25650b62fd367bae47ef185 is 20 bytes (an address), not 32 bytes. The jq filter will never match. Replace with the correct keccak256 of OptimismMintableERC20Created(address,address,address).

Minor

• ## Contract Addresses → ## Contract addresses (sentence case per docs convention — only proper nouns capitalized).
• Testnet L1 addresses are lowercase hex; mainnet L1 addresses are EIP-55 checksummed. Use a consistent format throughout the table.

[claude]

Review: LGTM — previous threads were incorrect

I've resolved all 5 prior review threads; the concerns they raised don't apply to the current code:

• ABI signature (uint32 thread): bridgeERC20(address,address,uint256,uint32,bytes) is correct. Position 4 is _minGasLimit, which is uint32 in the OP Stack Standard Bridge — not _amount.
• Event selector (two threads): The code uses 0x52fe89dd5930f343d25650b62fd367bae47088bcddffd2a88350a6ecdd620cdb — 64 hex chars (32 bytes), correct length for a keccak256 topic. The threads referenced a 20-byte hash that never appeared in this diff.
• Bash line continuation (two threads): There are no inline # comments after \ in any code block. Clean line continuations throughout.

The guide is structurally correct and ready to merge.

[Troublor]

@SilasZhr shouldn't the bridge ERC20 doc belong to the user doc instead of dev doc? Similar to "Getting Ethers on Mainnet", which is essentially bridging ETH.

[Troublor]

I see. It is meant for the dapp developers who wants to bring their token on mainnet to MegaETH.