[wieslawsoltes]

FileSystemDirectoryHandle.getDirectoryHandle(name, { create: true }) now crosses a typed, bounded native broker and resolves to a derived opaque directory handle. The implementation consumes AppScene #169, preserves existing directory contents, maps native cancellation/security/type/resource outcomes to browser errors, and retires pending work across navigation without exposing paths or native objects.

Validation:

• Chrome 153 oracle: 3/3 subtests pass; evidence SHA-256 837bedb8a5065b5b3bf10a6a287f6c4b19203f33965a5f2cb1d47975c4900c70
• create-directory broker and C11 ABI gates pass (10,000 operations, 100 retire cycles, RSS/FD bounds)
• native runtime compiles and executes the new create/enumerate/status/duplicate-completion cases before a documented pre-existing aggregate writer assertion (write after close did not reject TypeError); exact base build reproduces the same assertion
• file-system handle lifetime gate passes: 100 cycles, drained queues, bounded heap/RSS
• native symbol export and binary interop contract pass

Closes #409
Refs #248
Refs SceneTech/AppScene#168