Open a full-screen preview when tapping a gallery item

Tapping a gallery tile/row opens the existing media preview scoped to that gallery's attachments, paging between them. Introduces a typed MediaPreviewItemID (replacing the stringly-typed preview identifier) and a gallery-scoped TimelineMediaPreviewDataSource; the tap routes through TimelineInteractionHandler/TimelineViewModel. Non-previewable (.other) items are skipped without shifting the tapped index.

Co-authored-by: svetoslav.mitov <svetoslav.mitov@sportinno.com>

just use id instead of previewID

removed horrible multiline ternary

pr suggestions

remove redundant code

remove empty caption display + gallery uses the appropriate media timeline actions

ElementX/Sources/Screens/Timeline/View/TimelineItemViews/GalleryRoomTimelineView.swift

@@ -27,15 +27,13 @@ struct GalleryRoomTimelineView: View {
                 if usesListLayout {
                     GalleryListView(items: timelineItem.content.items,
                                     mediaProvider: context?.mediaProvider,
-                                    contentScannerService: context?.contentScannerService) { _ in
-                        // Tapping to open the full-screen preview lands in a follow-up.
-                    }
+                                    contentScannerService: context?.contentScannerService,
+                                    onItemTap: tap)
                 } else {
                     GalleryGridView(items: timelineItem.content.items,
                                     mediaProvider: context?.mediaProvider,
-                                    contentScannerService: context?.contentScannerService) { _ in
-                        // Tapping to open the full-screen preview lands in a follow-up.
-                    }
+                                    contentScannerService: context?.contentScannerService,
+                                    onItemTap: tap)
                 }
                 
                 if hasMediaCaption {
@@ -61,6 +59,10 @@ struct GalleryRoomTimelineView: View {
                               boostFontSize: timelineItem.shouldBoost)
         }
     }
+    
+    private func tap(index: Int) {
+        context?.send(viewAction: .galleryItemTapped(itemID: timelineItem.id, index: index))
+    }
 }
 
 // MARK: - Previews