v0.3.0

Added

• Recursive type aliases whose arms include dx.Model subclasses now
  translate to a panproto-native closed sum sort. The motivating shape
  is a Component alias mixing primitives, Models, and JSON-compatible
  containers; the alias name becomes the panproto sort, with one
  Operation per arm declared as a constructor and the sort's
  SortClosure set to Closed against that constructor list. Wire
  format for an arm value is a single-key JSON object whose key is
  the constructor name (matches panproto's term-of-closed-sort
  encoding). Lists round-trip as tuples to satisfy the tuple-based
  FieldValue invariant. Cycles in the value graph raise
  ValueError rather than recurse. (#2)
• dx.TaggedUnion subclasses are now usable directly as a field value
  type. dict[str, Parameter], tuple[Parameter, ...], and a bare
  param: Parameter annotation all work, with dispatch via the
  variant's discriminator field. The translation contributes a closed
  sum sort and per-variant constructor ops to the parent Model's
  Theory; the on-wire format is the variant's natural model_dump
  (no envelope, since the discriminator is already in the payload).
  (#5)
• TypeTranslation gains optional auxiliary_sorts and
  auxiliary_ops tuples that let a translation contribute extra
  panproto sort and operation declarations to the parent Model's
  Theory. Currently produced by the recursive Model-ref alias and
  TaggedUnion translations; build_theory_spec walks them and
  dedupes by name. Empty for every other translation.
• inner_kind = "sum" joins the documented set of TypeTranslation
  inner-kind values. model_dump routes sum-sort fields through their
  encoder so the constructor-tag dispatch survives JSON round-trip.

Notes

• Recursive aliases that aren't pure JSON-shape and aren't
  Model-ref-shape (e.g. one admitting bytes, Decimal, or a
  non-Model class) continue to raise TypeNotSupportedError with a
  clear message.
• Panproto's Theory.sorts and Theory.ops attributes are list-typed
  at runtime, contrary to the shipped _native.pyi stub which marks
  them as methods. Tests that introspect a built Theory treat them
  as data.