Minor.Query Object Api

BREAKING CHANGE: Replace the public QueryBuilder API with Query objects that can be created with query(table) and executed with db.exec(...).

db.query(table) still provides the same chainable ergonomics, but it now returns the public Query class in a database-bound form instead of a separate QueryBuilder type. db.exec(...) now accepts only raw SQL or Query values, and unbound terminal methods like first(), count(), exists(), insert(), update(), and delete() return Query objects instead of separate command descriptor types.

The incidental QueryMethod type export has also been removed; use Database['query'] or QueryForTable<table> when you need that type shape.