A leading NOT next to an operator was miscompiled: the bleve compiler left the consumed term in `next`, so `NOT x AND y` dropped `y` and produced a self-contradicting clause; the OpenSearch transpiler checked nextOp==AND before prevOp==NOT, so the negated term landed in `must` instead of `must_not`. NOT is unary and binds to the node directly after it regardless of what follows. This also fixes `mediatype:file AND <term>` (the web Files filter) at the root, so the earlier mediatype:file group workaround is dropped.