fix(rpiv-pi,rpiv-workflow): temper the drifted pattern copies; single-source the segment (review I3/Q2)

2136ef72 tempered both production encodings of the artifact-path pattern
but missed the two deliberately-inlined copies in the framework's
collection/replay harnesses (runner.test.ts, runner/resume.test.ts) — the
tests still blessed "..'-bearing paths production now fatals on, the exact
class the tempering targets, and the repo's most recurrent bug family.
Both copies are tempered in place (the cross-package import stays
deliberately avoided).

In artifact-collector.ts the tempered segment now has ONE encoding: a
TEMPERED_SEGMENT string builds both RPIV_ARTIFACT_PATTERN and
rpivBucketCollector's pattern, so the two in-file encodings can never
drift either.