feat: use endpointUri for cross-route drill-down instead of label parsing

Server:
- Add endpointUri to PositionedNode (from RouteNode)
- Add fromEndpointUri to RouteSummary (catalog API)
- Catalog controller resolves endpoint URI from diagram store

UI:
- Build endpointRouteMap from catalog's fromEndpointUri field
- Drill-down uses exact match on node.endpointUri against the map
- Remove label parsing heuristics (extractTargetEndpoint, camelToKebab)

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

@@ -666,7 +666,7 @@ public class ElkDiagramRenderer implements DiagramRenderer {
                             getAbsoluteX(wrapperElk, rootNode),
                             getAbsoluteY(wrapperElk, rootNode),
                             wrapperElk.getWidth(), wrapperElk.getHeight(),
-                            wrapperChildren));
+                            wrapperChildren, null));
                     ctx.compoundInfos.put(wrapperId, new CompoundInfo(wrapperId, Color.WHITE));
                 }
                 // Handler children in order: DO_FINALLY first, then DO_CATCH
@@ -693,7 +693,8 @@ public class ElkDiagramRenderer implements DiagramRenderer {
                 rn.getType() != null ? rn.getType().name() : "UNKNOWN",
                 absX, absY,
                 elkNode.getWidth(), elkNode.getHeight(),
-                children
+                children,
+                rn.getEndpointUri()
         );
     }