fix(#824): enforce exact skill link ownership

packages/mosaic/framework/tools/_scripts/mosaic-sync-skills

@@ -242,14 +242,10 @@ prune_stale_links_in_target() {
       continue
     fi
 
-    resolved="$(readlink -f "$link_path" 2>/dev/null || true)"
-    if [[ -z "$resolved" ]]; then
-      rm -f "$link_path"
-      echo "[mosaic-skills] Removed stale broken skill link: $link_path"
-      continue
-    fi
-
-    if [[ "$resolved" == "$MOSAIC_HOME/"* ]]; then
+    # -m resolves lexical dangling targets too. If resolution fails, ownership
+    # is unproven and the link must be preserved.
+    resolved="$(readlink -m "$link_path" 2>/dev/null || true)"
+    if [[ -n "$resolved" && "$resolved" == "$canonical_real/"* ]]; then
       rm -f "$link_path"
       echo "[mosaic-skills] Removed stale retired skill link: $link_path"
     fi