fix: exclude handler compound children from main flow ELK graph

Root cause found: RouteGraph.getNodes() is a FLAT list that includes
handler compound children (log8, setBody1, etc.) as top-level entries
alongside the main flow nodes. The handler separation only identified
the compound PARENTS (ON_EXCEPTION) but not their children, so 7
handler children leaked into rootNode as main flow nodes, causing
ELK to place the real main flow at wrong Y positions.

Fix: two-pass separation — first identify handler compounds and
collect ALL descendant IDs, then build mainNodes excluding both
handler compounds AND their descendants.

Debug logging left in temporarily for verification.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/diagram/ElkDiagramRenderer.java

@@ -206,15 +206,24 @@ public class ElkDiagramRenderer implements DiagramRenderer {
         Map<String, Color> nodeColors = new HashMap<>();
         Set<String> compoundNodeIds = new HashSet<>();
 
-        // Separate handler sections from main flow nodes
+        // Separate handler sections from main flow nodes.
+        // graph.getNodes() is a FLAT list that includes handler compound children
+        // as top-level entries. We must identify and exclude them.
         List<RouteNode> mainNodes = new ArrayList<>();
         List<RouteNode> handlerNodes = new ArrayList<>();
+        Set<String> handlerDescendantIds = new HashSet<>();
         if (graph.getNodes() != null) {
+            // First pass: identify handler compounds and collect their descendant IDs
             for (RouteNode rn : graph.getNodes()) {
                 if (rn.getType() != null && HANDLER_SECTION_TYPES.contains(rn.getType())
                         && rn.getChildren() != null && !rn.getChildren().isEmpty()) {
                     handlerNodes.add(rn);
-                } else {
+                    collectDescendantIds(rn.getChildren(), handlerDescendantIds);
+                }
+            }
+            // Second pass: main flow = everything that isn't a handler or handler descendant
+            for (RouteNode rn : graph.getNodes()) {
+                if (!handlerNodes.contains(rn) && !handlerDescendantIds.contains(rn.getId())) {
                     mainNodes.add(rn);
                 }
             }
@@ -643,6 +652,16 @@ public class ElkDiagramRenderer implements DiagramRenderer {
     }
 
     /** Recursively collect all node IDs from a tree. */
+    /** Collect IDs of all RouteNode descendants (for handler separation). */
+    private void collectDescendantIds(List<RouteNode> nodes, Set<String> ids) {
+        for (RouteNode n : nodes) {
+            ids.add(n.getId());
+            if (n.getChildren() != null) {
+                collectDescendantIds(n.getChildren(), ids);
+            }
+        }
+    }
+
     private void collectAllIds(PositionedNode node, Set<String> ids) {
         ids.add(node.id());
         if (node.children() != null) {