feat: ghost adapter

[znevo]

Ghost adapter

Adds a DEX adapter for Ghost's cross-collateral router, following the
UniswapV2/V3 adapter pattern.

executeGhost approves the gross amountIn to the source router and calls
transferRemoteTo, crediting recipient on the target side. amountIn is the
total input budget (principal + fee); the principal forwarded to the router is
derived on-chain rather than encoded in calldata, since the real amountIn
can differ at execution time.

GhostQuoter resolves Ghost's fee contract (cross-collateral routing → linear /
offchain-quoted-linear, with wildcard and default-router fallbacks) and inverts
the fee curve fee(x) = min(maxFee, x·maxFee / (2·halfAmount)) to find the
largest principal where principal + fee(principal) ≤ amountIn. Output and
unused input are read from balance deltas; amountUnused is at most 1 wei of
integer-division dust.

Calldata is (address sourceRouter, address targetRouter).

• No native-token leg.
• Uses TokenHelper and CalldataDecoder per the contributing guidelines.
• Tests in test/adapters/ghost/GhostAdapter.t.sol.
• "Allow edits from maintainers" is enabled.

[minhtr09]

Hi @znevo, please check the other adapter test files to follow the existing pattern. The fuzzed value should be amountIn and it should be passed to the execute function argument, not used as the Ghost principal amount.

For Ghost, amountIn is the total input budget including fees. The principal amount passed to transferRemoteTo should be derived from amountIn, not encoded directly in data, because the actual amountIn may change on-chain.

[znevo]

Thanks @minhtr09, this is addressed now.

I'd originally baked the amount into data to keep the adapter light, on the assumption that if the on-chain amountIn came in different it would just revert the same way any swap does on slippage. Deriving it on-chain avoids that failure mode entirely, so I've taken that route:

• data now carries only (sourceRouter, targetRouter). The principal is derived on-chain in GhostQuoter from amountIn, so it tracks the real on-chain amountIn rather than a value baked into calldata.
• The fuzz test now passes amountIn to executeGhost, following the UniswapV2 adapter test.

[LuuOW]

Technical audit: implementation details and logic patterns verified for system integrity.

[minhtr09]

Hi @znevo