fix: mutation error notifications, query error state, ratio guards, memoization, composite ids, docs accuracy

apps/docs/docs/widgets/downloads/index.mdx

@@ -44,7 +44,7 @@ import contextMenuImg from './img/context-menu.png';
 
 - **Responsive table** — columns automatically adapt to widget width, hiding less important columns at smaller sizes
 - **Sortable columns** — click any column header to sort ascending/descending
-- **Column customization** — toggle, reorder, resize, and pin columns via the header menu; preferences persist in local storage
+- **Column customization** — choose which columns to display via the widget options panel
 - **Right-click context menu** — pause, resume, delete downloads, or copy download names directly from the context menu
 - **Row expansion** — click any row to see full details inline without opening a separate modal
 - **Hover tooltips** — hover a download name to see size, speeds, ETA, ratio, and category
@@ -84,7 +84,6 @@ import contextMenuImg from './img/context-menu.png';
 - **Right-click** any download to open a context menu with pause/resume, delete, and copy actions
 - **Click** any row to expand it and see full download details inline
 - **Hover** a download name for a quick stats tooltip
-- **Column header menu** — show/hide, reorder, resize, or pin columns (reset via the columns button in the footer)
 - **Stats toggle** — show or hide the global stats bar from the footer
 - **Pause / Resume** all downloads using the footer controls
 - **Filter** by integration or status using the filter button in the footer