fix(desktop): v2 sidebar section count reflects visually grouped workspaces (#3544)

Ungrouped workspaces that render after a section header are already
visually grouped with that section (shared accent color, collapse
together) and get committed into it on next drag. The count, however,
was reading section.workspaces which only included workspaces whose DB
sectionId already matched — so a freshly created section showed "(0)"
while the user sees N workspaces beneath it.

Reparent those workspaces into section.workspaces in the data layer so
the count matches the visual grouping and DnD commit behavior.

Author: saddlepaddle

apps/desktop/src/renderer/routes/_authenticated/_dashboard/components/DashboardSidebar/hooks/useDashboardSidebarData/useDashboardSidebarData.ts

@@ -324,9 +324,31 @@ export function useDashboardSidebarData() {
 				sectionMap: _sectionMap,
 				...sidebarProject
 			} = resolvedProject;
-			sidebarProject.children = childEntries
+
+			const sortedChildren = childEntries
 				.sort((left, right) => left.tabOrder - right.tabOrder)
 				.map(({ child }) => child);
+
+			// Ungrouped workspaces rendered after a section header are visually
+			// grouped with that section (shared accent, collapse-together) and will
+			// be committed into it on next DnD. Reparent them here so section counts
+			// match what the user sees.
+			const children: DashboardSidebarProjectChild[] = [];
+			let currentSection: DashboardSidebarSection | null = null;
+			for (const child of sortedChildren) {
+				if (child.type === "section") {
+					currentSection = child.section;
+					children.push(child);
+				} else if (currentSection) {
+					currentSection.workspaces.push({
+						...child.workspace,
+						accentColor: currentSection.color,
+					});
+				} else {
+					children.push(child);
+				}
+			}
+			sidebarProject.children = children;
 			return [sidebarProject];
 		});
 	}, [