5.0.5

Added

• Generic type narrowing on the primitive field factories. Pass an explicit
  type argument to t.int8() / t.string() / etc. to refine the inferred
  field type, while the wire encoding is unchanged:

  const MoveInput = schema({
      moveX: t.int8<-1 | 0 | 1>(),         // typed -1 | 0 | 1, still a 1-byte int8
      team:  t.string<"red" | "blue">(),   // typed "red" | "blue", still a string
  });

  Each t.<primitive>() now has two call signatures: the bare call returns the
  natural type for the codec (t.int8() → number), and an explicit type
  argument returns FieldBuilder<T>. This is an overload pair rather than a
  defaulted generic (<T extends TBase = TBase>()): a defaulted free type
  parameter gets captured as any during schema()'s self-referential field
  inference (and undefined extends any then flips every field optional), so
  the bare form must stay a concrete FieldBuilder<TBase>.

  The refinement is a type-level assertion only — the wire still carries the
  codec's full range and the decoder writes whatever bytes arrive. Sound for
  server-authored state; for input schemas (untrusted client) keep validating /
  clamping on receipt.