fix(search): treat wildcard-free file_pattern as a path substring (#200)

search_graph file_pattern always returned 0 for a bare name like
"offer-server": cbm_glob_to_like produced the literal "offer-server",
so `file_path LIKE 'offer-server'` only matched a path equal to it, never
"src/offer-server/x.js". When the pattern contains no glob wildcards
(* or ?), wrap the LIKE as %pattern% so it matches anywhere in the path.
Explicit globs keep their semantics.

Closes #200.