fix: resolve UI bugs and pasting behavior

- Add global Cmd+V keyboard paste support for downloading links
- Restore striped background styling for alternate rows in download list
- Add ghost rows to seamlessly fill empty download space
- Map correctly formatted item size into the queue immediately
- Remove unused Tauri manager imports from backend

src/components/AddDownloadsModal.tsx

@@ -613,7 +613,8 @@ export const AddDownloadsModal = () => {
             destination: finalLocation,
             isMedia: item.isMedia,
             mediaFormatSelector: formatSelector,
-            queueId: selectedQueueId
+            queueId: selectedQueueId,
+            size: item.size || (item.sizeBytes ? formatBytes(item.sizeBytes) : undefined)
           });
         } catch (e) {
           console.error("Invalid URL or failed to add:", e);