Bounded, non-authoritative presentation of a PTC-Lisp value.
The original value remains authoritative. A preview may be truncated or may be replaced by a small fallback without changing evaluation outcome or continuation state.
@type cap() :: :depth | :items | :nodes | :output | :string
@type t() :: %PtcRunner.Lisp.ValuePreview.Result{ caps_hit: [cap()], sampled_keys: [String.t()], text: String.t(), truncated?: boolean() }