feat: add inspect mode to NodeFlowBehavior and enhance node drag logic with behavior checks

Author: pavanpodila

packages/vyuh_node_flow/lib/src/editor/node_flow_behavior.dart

@@ -50,6 +50,21 @@ enum NodeFlowBehavior {
     canZoom: true,
   ),
 
+  /// Inspect mode - view and select, but no modifications or rearrangement.
+  ///
+  /// Use this for runtime inspection where you want to select nodes to view
+  /// their state but prevent any layout changes. Ideal for execution/run modes
+  /// where the graph layout should remain stable.
+  inspect(
+    canCreate: false,
+    canUpdate: false,
+    canDelete: false,
+    canDrag: false,
+    canSelect: true,
+    canPan: true,
+    canZoom: true,
+  ),
+
   /// Presentation mode - display only, no interaction.
   ///
   /// Use this for embedded displays, thumbnails, or presentation contexts

packages/vyuh_node_flow/lib/src/nodes/node_container.dart

@@ -151,7 +151,8 @@ class NodeContainer<T> extends StatelessWidget {
                     createSession: () =>
                         controller.createSession(DragSessionType.nodeDrag),
                     // Drag lifecycle - unified for all node types
-                    isDraggable: !node.locked,
+                    // Check both node lock state AND behavior mode
+                    isDraggable: !node.locked && controller.behavior.canDrag,
                     onDragStart: (_) => controller.startNodeDrag(node.id),
                     onDragUpdate: (details) =>
                         controller.moveNodeDrag(details.delta),