## Function names should use mixedCase

**Severity**: `Info`
**ID**: `mixed-case-function`

Flags function names that do not follow `mixedCase`.

### What it does

Reports functions whose names contain embedded underscores, start with an uppercase letter, or
otherwise deviate from `mixedCase`. Leading and trailing underscores are preserved, and
single-character names are not checked. Test functions starting with `test`, `invariant_`, or
`statefulFuzz`, configured uppercase patterns (for example, `ERC20`), and external constant-style
getters are exempted.

### Why is this bad?

The Solidity style guide recommends `mixedCase` for function names. Consistent style makes call
sites uniform, helps editor tooling, and reduces friction in code review.

### Example

#### Bad

```solidity
function get_balance() external view returns (uint256);
function GetBalance()  external view returns (uint256);
```

#### Good

```solidity
function getBalance() external view returns (uint256);
```

### Configuration

Set `mixed_case_exceptions` under `[lint.lint_specific]` in `foundry.toml` to replace the default
list of allowed uppercase patterns (`ERC`, `URI`, `ID`, `URL`, `API`, `JSON`, `XML`, `HTML`, `HTTP`,
and `HTTPS`):

```toml
[lint.lint_specific]
mixed_case_exceptions = ["ERC", "URI", "NFT"]
```