queryOnce should preserve SingleResult type from source collection

[rohanajayjain]

When a collection is created with .findOne(), it's typed as Collection<T> & SingleResult, correctly indicating it returns at most one row. However, when this collection is passed to queryOnce, the SingleResult information is lost:

// Collection correctly typed as SingleResult
const collection = createLiveQueryCollection({
  query: (q) => q.from({ users }).where(...).findOne(),
}); // Collection<User> & SingleResult

// queryOnce wraps it in q.from(), losing SingleResult - returns User[] instead of User | undefined

const result = await queryOnce((q) => q.from({ user: collection }));
// ^? User[]  — have to destructure: const [user] = result

Expected behavior:

queryOnce should either:

1. Accept a SingleResult collection directly and return Promise<T | undefined>, or
2. Preserve the SingleResult marker through q.from() so InferResultType returns T | undefined instead of T[]

Current workaround:

const [result] = await queryOnce((q) =>
  q.from({ config: singleResultCollection }),
);

This works but loses type safety - result is typed as T | undefined only because of array destructuring, not because the type system knows it's a single-result query.