Quality cleanup across the 9-unit build (behavior-preserving, 89 tests green):
- extract createCeTaskWithLink so the work bridge and reconciler share one
provenance+link contract (prevents drift)
- discovery list scan probes readability via accessSync instead of reading and
discarding full file bytes
- makeError helper replaces ~7 duplicated CeArtifactError literals
- shared asString route helper; drop dead pipelineIds set; collapse a double
pipeline-state write and a redundant link re-query in advance
- resolveStageSkillCwd no longer takes params it ignores
061297b432