[codex] Extend Binance rebalancer routes for WETH

[nicholaspai]

What changed

• moved built-in rebalance route generation into src/rebalancer/buildRebalanceRoutes.ts
• refactored route construction around token-keyed BINANCE_NETWORKS_BY_SYMBOL and REBALANCE_CHAINS_BY_SYMBOL maps so Binance venue support and rebalancer enablement are configured separately
• expanded Binance routes to support WETH <-> USDC, WETH <-> USDT, and direct WETH <-> WETH transfers on direct Binance ETH networks
• added same-asset Binance routes for USDC <-> USDC and USDT <-> USDT so they can compete on estimated cost against CCTP and OFT routes
• colocated the same-asset Binance route generation with the CCTP/OFT route blocks and only emit those Binance routes when both chains are direct Binance networks for that asset
• taught the Binance adapter to treat on-chain WETH as Binance ETH, skip the swap leg for same-coin transfers, and avoid intermediate bridge legs for assets that cannot use them
• added helper coverage for Binance route math and route-generation coverage for the new WETH and same-asset stablecoin families
• documented the new route construction and Binance operational constraints in the rebalancer README

Why

The existing rebalancer/Binance flow was effectively limited to USDC and USDT swap routes. These changes open the path for WETH support and also let Binance compete directly with CCTP/OFT when the source and destination asset are already the same, while still avoiding same-asset Binance routes on chains that would require intermediate bridge legs.

The token-keyed network maps also make it easier to distinguish between:

• chains Binance currently supports for a token
• chains this repo currently wants the rebalancer to use for that token

Impact

Rebalancer route construction now exposes WETH-capable Binance families plus same-asset Binance stablecoin routes on direct Binance networks, and the Binance adapter can process both swap-backed routes and same-coin withdrawals safely.

Validation

• yarn build
• yarn test test/BinanceAdapter.helpers.ts test/RebalancerClient.buildRebalanceRoutes.ts

[nicholaspai]

this function should be better commented its unclear what's going on here and what its intended purpose is

[nicholaspai]

what does this hardcoded class variable do?