No way to search the watchlist by title

The entire point of a personal watchlist is "did I already add this?" and "where's the one I'm thinking of?" -- but once a user has more than one page of movies, there is no way to answer either question except by paging through everything by hand. This is the single most obviously missing piece of core watchlist functionality in the API as it stands today, and it's the most common thing a user of an app like this would reach for.

GET /api/movies can currently be narrowed only by watched (true/false) and paged with page/per_page. There is no way to search by title. MovieListQuerySchema does already declare a title field -- it was added as scaffolding for this ticket -- but list_movies() never reads it, so passing ?title=... is silently accepted and silently ignored.

curl -s "localhost:5000/api/movies?title=Reloaded" -H "Authorization: Bearer $TOKEN"

-> every movie the user owns, completely unfiltered -- "title" is accepted but silently ignored.

list_movies() already has the pattern to copy: it conditionally calls .filter_by(...) on base_query only when the watched query param was actually supplied (if query_args["watched"] is not None:). MovieListQuerySchema already declares and validates a title field as scaffolding for this ticket, so query_args["title"] is already available and None when the caller didn't pass it -- the view function just never reads it.

Look at how the existing watched filter is applied in list_movies(): it conditionally calls .filter_by(...) on base_query only when the query param was actually supplied (if query_args["watched"] is not None:). The title field on MovieListQuerySchema already gives you query_args["title"] the same way -- it's None when the caller didn't pass it. You'll want a substring, case-insensitive match against MovieEntry.title, not filter_by's exact-match semantics (SQLAlchemy has a column method built for exactly this).