The 17.2.2 compound-fragment matching splits commands on every unquoted
operator including `|`, so a downstream pipe stage like `grep x` in
`printf 'x\n' | grep x` became a standalone interception candidate and was
routed to the `grep` tool, which searches paths and cannot consume the
previous stage's stdout.
`extractFlatShellCommandSegments` now flags each segment that receives piped
stdin from a single unquoted `|`, and `interceptionCandidates` skips those:
a stdin-consuming stage cannot be replaced by a path-based dedicated tool.
Standalone (`grep pattern path`), first-stage (`grep x file | wc`), and
`&&`/`||`/`;`-sequenced commands still match.
Fixes#7496
roboomp
cbfbcd865e