// Package config loads and validates typed configuration files using viper and
// go-playground/validator.
//
// # Workflow
//
// Define a struct with mapstructure and validate tags, create a [Manager] with
// [NewManager], optionally configure hooks via [Manager.WithOpts], then call
// [Manager.Load] during startup. Use [Manager.C] or [Manager.Config] for quick
// access after load.
//
// # Environment overrides
//
// Set [ManagerOpts.EnvPrefix] or call [Manager.WithEnvOverride]. Nested keys use
// dots in YAML and underscores in env vars (for example MYAPP_DATABASE_USER).
//
// # Root directory discovery
//
// [RootDir] and [MustRootDir] locate a marker file by walking up from the working
// directory—useful when config lives near a repo root.
package config