refactor(superdoc): convert core/types/index.js to TypeScript (SD-2869)

Replaces 769 lines of JSDoc @typedef declarations with native TS
interfaces, type aliases, and re-exports. Each public name is preserved
verbatim (Config, Modules, FindReplace*, PasswordPrompt*, Surface*,
ContextMenu*, Document, User, etc.) so consumers that import from
'superdoc/types' or via the auto-derived assertion list see the same
shape.

Why TS instead of JSDoc:

The drift class SD-2863 catches lives in implementations that consume
the JSDoc typedefs. The typedef file itself was unchecked: a typedef
that referenced an undefined name silently shipped as `any`. Native
TypeScript declarations are checked by the compiler at every import
site, so the typedef-side cannot drift from the implementation it
describes.

Surface preservation:

- All 50+ exported names retained.
- Optional vs required field flags retained.
- Generic typedefs (SurfaceOutcome, SurfaceHandle) keep `<T = unknown>`.
- Nested @Property declarations inlined as nested object types rather
  than promoted to new named interfaces, to keep the public surface
  byte-equivalent.
- JSDoc `Object` becomes TS `object` (lowercase) which matches the
  resolved type consumers already saw.
- Re-exported types (Editor, StoryLocator, BookmarkAddress, etc.)
  emerge from the same `@superdoc/super-editor` module under the same
  names.

Verified: pnpm --filter superdoc run check:jsdoc passes (3 gated files
clean), the consumer-typecheck matrix passes 27/27, and the postbuild
declaration audit reports no FAIL findings.

Author: caio-pizzol