Routes `ktx wiki list` and `ktx wiki search` through the shared printList()
renderer so all four list/search commands now produce the same Clack-style
pretty box, TSV plain output, and JSON envelope. Adds a `--output` flag to
the wiki commands mirroring sl, and surfaces relevance score as a leading
dim badge ("87%") in pretty mode and a `score=` prefix in plain mode for
both wiki search and sl search. Empty results now emit a consistent
actionable hint across commands.