feat: add GEWU installer and service contracts

skills/kb-curate/SKILL.md

@@ -8,6 +8,6 @@ Read the pack's [evidence](../../protocols/EVIDENCE.md), [scope](../../protocols
 
 Identify the requested audit and bound its collection/budget. For a report-only request, do not submit proposals. Inspect candidate nodes, source revisions, dates and relationships before recommending a change. Similarity nominates candidates; it does not prove duplicates. Preserve incompatible claims and explain the conditions under which they differ.
 
-For requested corrections, submit typed stale flags, supersession or relationship proposals supported by inspected records. Merges, promotion and protected changes follow their separate policy/owner gates. Never silently delete a node, rewrite canonical files or treat read scope as change authority.
+For requested corrections, submit typed stale flags, supersession or relationship proposals supported by inspected records. Record material assumptions and limitations as distinct evidence-backed claim groups on the relevant node; do not infer them from an approach summary or relationship condition. Merges, promotion and protected changes follow their separate policy/owner gates. Never silently delete a node, rewrite canonical files or treat read scope as change authority.
 
-Report examined coverage, findings, proposed/accepted changes and unresolved exceptions. Unsupported curation tools remain unavailable; do not substitute raw SQL or filesystem edits.
+Report examined coverage, findings, proposed/accepted changes and unresolved exceptions. The service exposes typed `flag_stale`, `add_edge` and `upsert_node` proposals, but no duplicate merge, unlink or promotion operation. Keep those unavailable cases explicit; do not substitute raw SQL or filesystem edits.