feat(RingV2): add BSC support

[DreamXzxy]

Summary

• Add RingV2 deployment configuration for BSC.
• Add the BSC FewWrappedToken factory configuration.
• Add RingV2 BSC e2e coverage for BNB <-> ETH.

RingV2 already supports Ethereum. This PR only adds BSC configuration and tests.

BSC deployments

• Ring Swap Factory: 0x4De602A30Ad7fEf8223dcf67A9fB704324C4dd9B
• Few Factory: 0xEeE400Eabfba8F60f4e6B351D8577394BeB972CD
• Ring Swap Router: 0x20504f37A95eF80e3FC7476c4801fb39AaE6bAd0
• Ring Swap Pair Init Code: 0xa7ae6a5ec37f0c21bbdac560794258c4089b8ae3ffa6e3909b53c6091764a676
• Few Wrapped Token Init Code: 0x2bdba5734ddf754fb149ef1faa937956c52cfd1f24d68163a95f42d08ec06d38

Tests

• pnpm install --frozen-lockfile
• pnpm exec prettier --check src/dex/uniswap-v2/ring-v2.ts src/dex/uniswap-v2/uniswap-v2-e2e-bsc.test.ts
• pnpm run check:tsc
• pnpm run check:es
• pnpm run build
• git diff --check
• pnpm exec jest src/dex/uniswap-v2/uniswap-v2-e2e-bsc.test.ts --runInBand -t RingV2 --silent --forceExit

Notes

• WBNB/ETH has liquidity on RingV2 BSC, quotes in both directions, and is covered by the e2e tests.
• WBNB/USDT also quotes on-chain, but local e2e runs intermittently hit dex-lib's internal 3-second pricing timeout, so it is not included in the test coverage.
• USDC/WBNB, bBTC/WBNB, and DAI/WBNB were checked but do not currently have RingV2 pairs.

Note

Medium Risk
New on-chain addresses on a live chain; misconfiguration would break routing or few-wrap resolution, but changes are additive config and tests mirroring mainnet.

Overview
RingV2 is extended to BSC by adding network-specific DEX config alongside the existing mainnet setup.

RingV2Config gains a [Network.BSC] entry with BSC factory and router addresses (same initCode, fee, and pool gas assumptions as mainnet). FewWrappedTokenConfig gets a matching BSC block so few-wrapped token CREATE2 addresses resolve with the BSC few-wrap factory. Because dexKeysWithNetwork is built from these maps, BSC is picked up without other wiring changes.

BSC e2e coverage is added in uniswap-v2-e2e-bsc.test.ts: RingV2 SELL/BUY via swapExactAmountIn / swapExactAmountOut for BNB ↔ ETH in both directions.

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