UoE/Add results-per-page selector to statistics tables (DSpace#726)

Re-enable the standard ds-pagination "results per page" selector (gear) so users
can choose how many datasets to show per page (10/20/40/60/80/100), reusing the
built-in PaginationComponent control. The gear and pagination detail are shown
only when a report has more rows than fit on one page; pageSize remains the
default. The page slicing already honours the selected size.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: milanmajchrak

src/app/statistics-page/statistics-table/statistics-table.component.html

@@ -7,7 +7,7 @@ <h2 class="m-1">
 
   <ds-pagination [paginationOptions]="paginationOptions"
                  [collectionSize]="report.points.length"
-                 [hideGear]="true"
+                 [hideGear]="report.points.length <= pageSize"
                  [hidePaginationDetail]="report.points.length <= pageSize"
                  [hideSortOptions]="true"
                  [retainScrollPosition]="true">

src/app/statistics-page/statistics-table/statistics-table.component.spec.ts

@@ -148,6 +148,10 @@ describe('StatisticsTableComponent', () => {
       expect(pagination).toBeTruthy();
       expect(pagination.componentInstance.collectionSize).toEqual(2);
     });
+
+    it('should hide the page-size selector when everything fits on a single page', () => {
+      expect(de.query(By.directive(MockPaginationComponent)).componentInstance.hideGear).toBeTrue();
+    });
   });
 
   describe('when the report has more points than the page size', () => {
@@ -175,6 +179,12 @@ describe('StatisticsTableComponent', () => {
         .toEqual(numberOfPoints);
     });
 
+    it('should offer the page-size selector with its options when there is more than one page', () => {
+      const pagination = de.query(By.directive(MockPaginationComponent)).componentInstance;
+      expect(pagination.hideGear).toBeFalse();
+      expect(pagination.paginationOptions.pageSizeOptions).toEqual([10, 20, 40, 60, 80, 100]);
+    });
+
     it('should only render the first page of points', () => {
       expect(de.queryAll(By.css('[data-test="statistics-label"]')).length)
         .toEqual(component.pageSize);

src/app/statistics-page/statistics-table/statistics-table.component.ts

@@ -96,7 +96,9 @@ export class StatisticsTableComponent implements OnInit {
       // Unique per report AND scope so multiple tables paginate independently and a report doesn't pick up
       // another scope's page from the URL. report.id is `<dso-uuid>_<reportType>`, e.g. `<uuid>_TotalVisits`.
       id: `stats-${this.report.id}`,
+      // pageSize is the default; users can change it via the ds-pagination "results per page" selector.
       pageSize: this.pageSize,
+      pageSizeOptions: [10, 20, 40, 60, 80, 100],
       currentPage: 1,
     });