feat: add GEWU installer and service contracts

skills/kb-query/SKILL.md

@@ -6,7 +6,7 @@ description: Search and explain accepted GEWU knowledge within an explicit proje
 
 Read the pack's [evidence](../../protocols/EVIDENCE.md) and [scope](../../protocols/SCOPE.md) protocols, then use the [query pipeline](../../pipelines/query.md). Consult [contributions](../../protocols/CONTRIBUTIONS.md) for connection/availability rules; this skill performs no knowledge writes.
 
-Establish the question, scope and response budget. Use supported search/read tools and inspect the sources behind the strongest results. Preserve complete citation groups and required warnings. Widen scope only through an explicit request consistent with the user's task.
+Establish the question, scope and response budget. Use supported search/read tools and inspect the sources behind the strongest results. Use `list_sources` to browse the archived source catalog within that same authorized scope. Narrow searches with node-type or past-freshness filters when they match the question; filters do not widen authorization scope. Preserve complete citation groups and required warnings. Widen scope only through an explicit request consistent with the user's task.
 
 Separate accepted relationships from suggestions and distinguish disagreement from missing evidence. Answer with relevant conditions, as-of dates and source references near the claim. If retrieval is degraded, index-lagged or insufficient, state the observed limitation. Do not present a local draft, model recollection or unavailable service as an accepted GEWU result.