Align Solidity source contracts with the solidity style guide

[holyfuchs]

Align Solidity source contracts with the project style guide

Summary

Brings the contracts into conformance with the standard Solidity style guide.
https://docs.soliditylang.org/en/latest/style-guide.html

# FOUNDRY_BYTECODE_HASH=none strips the metadata hash, which otherwise
# always differs because it hashes the source text.
export FOUNDRY_BYTECODE_HASH=none

# 1) Capture bytecode on main.
git checkout main
forge build
forge inspect src/FCMVault.sol:FCMVault deployedBytecode > /tmp/before_vault.txt
forge inspect src/YieldTokenOracle.sol:YieldTokenOracle deployedBytecode > /tmp/before_oracle.txt

# 2) Capture bytecode on this branch.
git checkout holyfuchs/solidity-style-guide
forge build
forge inspect src/FCMVault.sol:FCMVault deployedBytecode > /tmp/after_vault.txt
forge inspect src/YieldTokenOracle.sol:YieldTokenOracle deployedBytecode > /tmp/after_oracle.txt

# 3) Compare — no output means the bytecode is identical.
diff /tmp/before_vault.txt /tmp/after_vault.txt
diff /tmp/before_oracle.txt /tmp/after_oracle.txt