The feed's channel-name match and the live search's term fold built their
LIKE pattern from the typed text as it was, so `_` and `%` acted as
wildcards: `build_log` also matched `buildXlog`. The term fold also tested
a substring, so a term already present inside a longer word (`cat` in
`category`) was never folded into search_terms. It now compares whole
terms, escaped.
`like_escape` moves from the Plex query module to `app.utils`, beside
`to_tsquery_str`, and every pattern built from typed text goes through it.
