modernize

type Change struct {
	RuleID      string `json:"rule_id"`
	Line        int    `json:"line"`
	Description string `json:"description"`
}

type Finding struct {
	RuleID  string `json:"rule_id"`
	Line    int    `json:"line"`
	Message string `json:"message"`
	Fixable bool   `json:"fixable"`
}

type Rule struct {
	ID          string
	Description string
	Severity    string // "error" or "warning"
	Check       func(root *yaml.Node, raw []byte) []Finding
	Fix         func(root *yaml.Node) []Change
}