Add Pivot Grid to PDF export demo

Added igx-pivot-grid to the PDF export demo component:
- Created sample pivot grid data with Product, Region, Quarter, Sales, and Units
- Added pivot configuration with row dimensions (Product, Region), column dimension (Quarter),
  and value aggregations (sum of Sales and Units)
- Added exportPivotGrid() method to export the pivot grid with configured options
- Updated UI to include Pivot Grid section with export button
- Updated documentation to mention pivot grid support

The demo now shows all major grid types: regular grid, tree grid, hierarchical grid,
and pivot grid, all exportable to PDF with the same configuration options.

Co-authored-by: kdinev <[email protected]>

Author: Copilot

src/app/grid-pdf-export/grid-pdf-export.sample.html

@@ -119,6 +119,25 @@ <h3>Hierarchical Grid (with Multi-Column Headers and Summaries)</h3>
         </igx-hierarchical-grid>
     </div>
 
+    <!-- Pivot Grid -->
+    <div class="grid-container">
+        <div class="grid-header">
+            <h3>Pivot Grid (with Aggregated Data)</h3>
+            <button igxButton="contained" (click)="exportPivotGrid()">
+                Export to PDF
+            </button>
+        </div>
+
+        <igx-pivot-grid #pivotGrid [data]="pivotGridData" [autoGenerate]="false" height="500px" width="100%">
+            <igx-pivot-configuration>
+                <igx-pivot-row pivotKeys='["Product", "Region"]'></igx-pivot-row>
+                <igx-pivot-column pivotKeys='["Quarter"]'></igx-pivot-column>
+                <igx-pivot-value field="Sales" aggregate="sum" displayName="Total Sales"></igx-pivot-value>
+                <igx-pivot-value field="Units" aggregate="sum" displayName="Total Units"></igx-pivot-value>
+            </igx-pivot-configuration>
+        </igx-pivot-grid>
+    </div>
+
     <div class="info-section">
         <h4>How to Use:</h4>
         <ol>
@@ -127,6 +146,7 @@ <h4>How to Use:</h4>
             <li>The PDF will be downloaded with your configured settings</li>
             <li>Tree and Hierarchical grids will show indentation in the exported PDF</li>
             <li>Multi-column headers and summaries are automatically included in the export</li>
+            <li>Pivot grids export with aggregated data values</li>
         </ol>
 
         <h4>Key Features:</h4>
@@ -136,6 +156,7 @@ <h4>Key Features:</h4>
             <li><strong>Hierarchy Support:</strong> Tree and Hierarchical grids export with proper indentation</li>
             <li><strong>Multi-Column Headers:</strong> Column groups are preserved in the exported PDF</li>
             <li><strong>Summaries Support:</strong> Grid summaries are automatically exported to PDF</li>
+            <li><strong>Pivot Grid Support:</strong> Pivot grids export with aggregated data and pivot structure</li>
             <li><strong>Multiple Grids:</strong> Export different grid types with the same configuration</li>
         </ul>
     </div>