feat(xtream): show category page info and preserve page state

Update category header and list views to provide clearer context
and improve navigation state handling.

- Display category name with current page/total pages when viewing a
  category (non-detail) so users see which page they're on.
- Add i18n "PAGE" key and fill "SELECT_CATEGORY" in translations for
  en/de/ru to support the new page label and existing messaging.
- Tidy live-stream layout template formatting and fix filter pipe
  spacing for consistency.
- Change no-channel-selected fallback to use the translated
  "PORTALS.SELECT_CATEGORY" string.
- Preserve category selection state on CategoryContentView init:
  only set selected category when the route category differs from
  the current selection to keep paging/scroll position when returning
  from a detail view.

These changes improve UX by making pagination explicit and avoiding
unnecessary state resets when navigating between list and detail.

apps/web/src/app/xtream-tauri/category-content-view/category-content-view.component.ts

@@ -46,7 +46,11 @@ export class CategoryContentViewComponent implements OnInit {
 
     ngOnInit() {
         const { categoryId } = this.activatedRoute.snapshot.params;
-        if (categoryId) this.store.setSelectedCategory(categoryId);
+        // Only set category if it's different from the currently selected one
+        // This preserves the page state when navigating back from detail view
+        if (categoryId && this.store.selectedCategoryId() !== Number(categoryId)) {
+            this.store.setSelectedCategory(categoryId);
+        }
     }
 
     onPageChange(event: PageEvent) {

apps/web/src/app/xtream-tauri/xtream-main-container.component.ts

@@ -53,9 +53,19 @@ export class XtreamMainContainerComponent implements OnInit {
             return this.translateService.instant('PORTALS.SELECT_CATEGORY');
         } else {
             const selectedCategory = this.xtreamStore.getSelectedCategory();
-            return selectedCategory
-                ? `Content for ${(selectedCategory as any).name}`
+            const categoryName = selectedCategory
+                ? (selectedCategory as any).name
                 : 'Category Content';
+
+            // Show page number when viewing category content (not detail view)
+            if (!this.xtreamStore.selectedItem() && this.xtreamStore.getTotalPages() > 1) {
+                const currentPage = this.xtreamStore.page() + 1; // +1 because page is 0-indexed
+                const totalPages = this.xtreamStore.getTotalPages();
+                const pageLabel = this.translateService.instant('PORTALS.PAGE');
+                return `${categoryName} (${pageLabel} ${currentPage}/${totalPages})`;
+            }
+
+            return `Content for ${categoryName}`;
         }
     }