feat: add rebasing token extension with on-chain sync tool

[ScreamingHawk]

Problem

Rebasing tokens change balances without a transfer. Aave aTokens also round transfers by a unit, so any fixed amount computed at quote time can be short by the time it executes. Trails hit this with aBasUSDC on Base: the origin fee transfer underflowed by 1 unit and the intent executed without collecting the fee. There is no flag for consumers to detect these tokens.

Change

• Adds extensions.rebasing: true, modelled on feeOnTransfer (present only when true).
• Adds tools/sync-rebasing.ts (pnpm sync-rebasing), which detects rebasing tokens on-chain by probing for selector pairs only rebasing implementations expose:
  • Aave v2/v3: UNDERLYING_ASSET_ADDRESS + scaledBalanceOf
  • Aave v1: underlyingAssetAddress + principalBalanceOf
  • Lido stETH: getPooledEthByShares + sharesOf
  • Origin OUSD: rebasingCreditsPerToken + nonRebasingSupply
  • Ampleforth: scaledBalanceOf + scaledTotalSupply
• Flags 285 tokens across mainnet, polygon, base, arbitrum, optimism, avalanche, bnb, gnosis and base-sepolia (277 Aave v2/v3, 5 Aave v1, stETH, OUSD, AMPL).
• ERC-4626 and share-price tokens (sUSDe, wstETH, cbETH, rETH) are not flagged. Their balances don't move, so fixed-amount math against them holds.
• Documents both sync-rebasing and the existing sync-fee-on-transfer tool in the README, and links both from the token schema.

Notes

• Each probe carries a totalSupply sentinel. Public RPCs silently drop calls from large multicalls, which otherwise reads as "not rebasing". Failed sentinels are retried in smaller batches, then as individual eth_calls.
• 15 tokens could not be probed and are reported, not assumed clean. None are rebasing. 7 of them are Aave Pool contract addresses wrongly listed as tokens, which is a pre-existing data issue left untouched here.
• Removing the rebasing key from every changed file gives JSON identical to master, and re-running --write is a no-op.