WIP Prevent zero shares being deposited

[naddison36]

Summary

• Revert LP deposits that would mint zero shares.
• Add a regression test covering the rounding case where convertToShares(assets) returns 0.

Details

convertToShares() rounds down, so if totalAssets() is slightly greater than totalSupply(), a very small deposit can transfer liquidity assets while minting zero LP shares. _deposit() now checks the computed share amount before transferring assets and reverts with ARM: zero shares when the deposit would mint nothing.

Testing

• forge test --match-path test/unit/OriginARM/Deposit.sol

Contract Sizes

forge build --sizes reports:

Contract	Runtime Size	Runtime Margin
EthenaARM	24,021 bytes	555 bytes
EtherFiARM	24,636 bytes	-60 bytes
LidoARM	24,544 bytes	32 bytes
OriginARM	23,692 bytes	884 bytes

EtherFiARM is currently 60 bytes over the EIP-170 runtime size limit, so forge build --sizes exits with a size-limit error.