First, we still need a way to pass a raw, unsafe query to qsprintf(...) so we can apply .sql migrations. There's no way to make these "safe" so introduce a new "raw unsafe query" conversion which works like the old %Q: %Z.
Second, when bin/storage adjust adds or modifies keys, it needs to run a query like this:
ALTER TABLE x ADD KEY y (u, w);
The (u, w) part is usually a list of columns (same as %LC) but may look like (u(16), w(64)) if the key is on prefix substrings of the column values.
Introduce %LK to escape this particular kind of column list grammar.