Hoist dataset (FROM) clause when wrapping a query into DESCRIBE

ldh:wrap-describe nested the original query — including its FROM / FROM NAMED
dataset clause — as a subquery inside DESCRIBE * WHERE { … }. A dataset clause
is only legal on the outermost query, so any view query carrying a FROM (e.g.
FROM <urn:x-arq:UnionGraph>) became an invalid subquery and the SPARQL endpoint
returned 400. Result-set views (ldh:View, all modes) always go through
ldh:RenderView → ldh:wrap-describe, so they all broke; charts (ResultSetChart)
bypass this path, which is why FROM works there.

Hoist the dataset clause up to the wrapping DESCRIBE and strip it from the
nested subquery. No-op for queries without a dataset clause, so fully
backwards-compatible.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: namedgraph

src/main/webapp/static/com/atomgraph/linkeddatahub/xsl/bootstrap/2.3.2/client/query-transforms.xsl

@@ -104,12 +104,28 @@ extension-element-prefixes="ixsl"
             <json:array key="variables">
                 <json:string>*</json:string>
             </json:array>
+            <!-- Hoist the dataset (FROM / FROM NAMED) clause up to the wrapping DESCRIBE.
+                 A dataset clause is only legal on the outermost query, so it cannot remain
+                 on the SELECT once that becomes a subquery (otherwise: SPARQL parse error).
+                 No-op for queries without a dataset clause, so fully backwards-compatible. -->
+            <xsl:copy-of select="json:map[@key = 'from']"/>
             <json:array key="where">
-                <xsl:sequence select="."/>
+                <xsl:apply-templates select="." mode="ldh:strip-from"/>
             </json:array>
         </json:map>
     </xsl:template>
 
+    <!-- strip the (now hoisted) top-level dataset clause off the nested subquery -->
+
+    <!-- identity transform -->
+    <xsl:template match="@* | node()" mode="ldh:strip-from">
+        <xsl:copy>
+            <xsl:apply-templates select="@* | node()" mode="#current"/>
+        </xsl:copy>
+    </xsl:template>
+
+    <xsl:template match="/json:map/json:map[@key = 'from']" mode="ldh:strip-from" priority="1"/>
+
     <!-- add parallax step -->
 
     <!-- identity transform -->