[crowlKats]

Fixes #426
Fixes #427

A type imported from a file that isn't a documented entrypoint, but which another entrypoint re-exports under a different name, was rendered as plain text:

// a.ts
import { Data } from "./_util.ts";
export function f(): Data {}
// b.ts
export { type Data as Foo } from "./_util.ts";

Data in f's signature now links to b.ts/~/Foo.html.

• The parser resolves each named/default import to its declaration (following re-exports) and records it as a new optional location on Import.
• lookup_symbol_href uses that location to find the documented re-export via the reference index when the import source isn't a documented file. Member paths work too (Util.Options → Helpers.Options).
• js/types.d.ts mirrors the new field.

The other two cases from the issues (Foo.Data through an import, and import { Data as Foo } alongside a local Data) already worked on main; regression tests cover all of them.