Api Learn Paths Alias

GET /api/learning/paths response.

paths is REQUIRED (F4 schema tightening 2026-04-29). The handler in routes/routes_education_fastapi/paths.py always returns LEARNING_PATHS_PUBLIC which is initialized to {"paths": []} on every code path (load-success, load-failure fallback). Marking it required activates the F2.2 boundary test as a real assertion rather than a trivial-pass.

count stays Optional — the handler doesn't compute it (it's derivable from len(paths) client-side; including a server-side count would require a backend change which isn't in scope here).