Add sort order to GET /notes

GET /notes always returns results ordered by id (i.e. creation order), with no way for a client to ask for anything else -- no newest-first, no alphabetical. A sort query parameter has already been added to the route in app/main.py and threaded through to crud.list_notes, but crud.list_notes raises NotImplementedError for any non-None sort value, valid or not. The default (no sort given) path is completely unaffected and still works exactly as before. Any real notes UI -- a "recently updated" view, an alphabetical list -- needs this before it can offer anything beyond raw insertion order.

crud.list_notes raises NotImplementedError for any non-None sort value passed through from the already-wired-up query parameter in app/main.py, regardless of whether that value is valid or garbage.

cd fastapi/notes_api source .venv/bin/activate uvicorn app.main:app --reload & curl -s "http://127.0.0.1:8000/notes?sort=title_asc"

-> NotImplementedError: sort is not implemented yet -- see ticket 05

There are two separate pieces here. First, ordering: translating a sort keyword into a SQLAlchemy .order_by() clause on top of the existing filtered query. Second, validation: rejecting an unrecognized sort value as a client error (422), not as a 500 or a silent fallback to default order -- right now sort is typed as a plain str | None in the route signature, so FastAPI has no way to know which values are valid and lets anything through to crud.list_notes. Getting the validation piece "for free" from FastAPI/Pydantic's own request validation, rather than hand-rolling an if/raise inside the endpoint body, is the more idiomatic approach in a codebase that leans on Pydantic models specifically so /docs and validation stay accurate and automatic.

For the validation half: look at how sort's type is declared in the list_notes route in app/main.py, and how FastAPI/Pydantic can validate a query parameter against a fixed, known set of string values automatically instead of accepting any str. For the ordering half: look at the TODO comment next to the NotImplementedError in crud.list_notes -- you'll need a mapping from each valid sort value to the matching Note column and direction, applied via .order_by() on the existing query before it's executed.