fix: export transiently referenced types

[achingbrain]

When we export a function like:

export function (foo: Bar): Baz {
  return { ... }
}

We have to also export the Bar type and any types it references, otherwise typedoc cannot create the API docs for us.

Also swaps instances of (default: foo) to use @default jsdoc tags.

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if necessary (this includes comments as well)
• I have added tests that prove my fix is effective or that my feature works