* fix(call-path): keep caller-only unknown coverage from blocking not_found
build_call_path expands only callee edges, so relationship coverage that
is unknown solely because callers are unobservable (the modern headless
IDA profile) no longer marks the searched callee closure incomplete.
The caller caveat stays visible in limitations, and callee-side unknowns
still yield unknown. Fixes#2322.
* test(call-path): cover IDA-capped callees beside unknown callers
Greptile review noted the poll-timing coverage only exercised unknown
callees, leaving the partial callees IDA returns at its 500-result cap
untested. Add the combined unknown-callers/partial-callees case:
isCallerOnlyUnknownCoverage must stay false and buildCallPath must keep
search_scope.exhaustive false, so a future change cannot silently report
not_found when IDA has omitted callees.
