DataGrid: add AI Assistant demo page (#32822)

Author: anna-shakhova

apps/demos/Demos/DataGrid/AIAssistant/AIAssistant@2x.png

@@ -0,0 +1,18 @@
+With our v26.1 release, we will extend the AI-powered capabilities of both the DevExtreme [DataGrid](https://js.devexpress.com/Documentation/Guide/UI_Components/DataGrid/Overview/) and [TreeList](https://js.devexpress.com/Documentation/Guide/UI_Components/TreeList/Overview/). We plan to introduce a DevExtreme Chat-based AI assistant that will allow you to use natural language to interact with DataGrid/TreeList. The DataGrid/TreeList AI assistant will be able to complete the following actions:
+* Sort, filter, search, and group data.
+* Resize, reorder, fix/unfix, and show/hide columns.
+* Change pagination settings.
+<!--split-->
+
+This feature is particularly well suited for the following usage scenarios:
+
+* **Large Datasets**: Use the power of AI to browse large data sets. Apply complex filter values with natural language.
+
+
+* **Complex Grid Configurations**: Allow users to specify complex display preferences quickly.
+
+
+* **Accessibility-first Applications**: Allow users to interact with your application in a manner that is most appropriate for each specific situation: while at their desk, or on the go (when their hands are busy and they require voice commands to interact with your app).
+
+
+* **Replicable Configurations**: Apply the same prompt to recreate complex grid configurations across sessions. Reduce time spent on tedious layout adjustments.

apps/demos/Demos/DataGrid/AIAssistant/description.md

@@ -595,6 +595,20 @@
               }
             ]
           },
+          {
+            "Name": "AI Assistant",
+            "Equivalents": "",
+            "Demos": [
+              {
+                "Title": "AI Assistant",
+                "Name": "AIAssistant",
+                "Widget": "DataGrid",
+                "Badge": "Roadmap",
+                "DemoType": "Web",
+                "RoadmapSurveyUrl": "https://www.devexpress.com/support/surveys/devextreme-roadmap-2026-ai-assistant.xml"
+              }
+            ]
+          },
           {
             "Name": "Master-Detail",
             "Equivalents": "preview row",