fix(site): hide table headers during loading and empty states on workspaces page (#23446)

## Problem

When the workspaces table transitions between states (loading →
populated, or populated → empty search results), the table column
headers visibly jump. This happens because the Actions column's width is
content-driven: when workspace rows are present, the action buttons give
it intrinsic width, shrinking the Name/Template/Status columns. When the
body is empty or loading, the Actions column collapses to zero, and the
other columns expand to fill the space.

## Solution

Hide the header content during loading and empty states using
`visibility: hidden` (Tailwind's `invisible` class), which preserves the
row's layout height but hides the text. This prevents the visual jump
since headers aren't visible during the states where column widths
differ.

- **Loading**: first column shows a skeleton bar matching the body
skeleton aesthetic; other columns are invisible
- **Empty search results**: all header content is invisible
- **Populated**: headers display normally

---------

Co-authored-by: Jaayden Halko <jaayden@coder.com>

site/src/pages/WorkspacesPage/WorkspacesPageView.stories.tsx

@@ -195,6 +195,13 @@ export const AllStates: Story = {
 	},
 };
 
+export const Loading: Story = {
+	args: {
+		workspaces: undefined,
+		count: undefined,
+	},
+};
+
 export const AllStatesWithFavorites: Story = {
 	args: {
 		workspaces: allWorkspaces.map((workspace, i) => ({

site/src/pages/WorkspacesPage/WorkspacesTable.tsx

@@ -1,4 +1,3 @@
-import Skeleton from "@mui/material/Skeleton";
 import {
 	BanIcon,
 	CloudIcon,
@@ -43,8 +42,8 @@ import { ConfirmDialog } from "#/components/Dialogs/ConfirmDialog/ConfirmDialog"
 import { ExternalImage } from "#/components/ExternalImage/ExternalImage";
 import { VSCodeIcon } from "#/components/Icons/VSCodeIcon";
 import { VSCodeInsidersIcon } from "#/components/Icons/VSCodeInsidersIcon";
+import { Skeleton } from "#/components/Skeleton/Skeleton";
 import { Spinner } from "#/components/Spinner/Spinner";
-import { Stack } from "#/components/Stack/Stack";
 import {
 	Table,
 	TableBody,
@@ -111,47 +110,57 @@ export const WorkspacesTable: FC<WorkspacesTableProps> = ({
 	chatsByWorkspace,
 }) => {
 	const dashboard = useDashboard();
+	const isLoading = !workspaces;
+	const isEmpty = workspaces && workspaces.length === 0;
+	const hideHeaders = isLoading || isEmpty;
 
 	return (
 		<Table>
 			<TableHeader>
 				<TableRow>
 					<TableHead className="w-1/3">
-						<div className="flex items-center gap-5">
-							<Checkbox
-								disabled={!workspaces || workspaces.length === 0}
-								checked={
-									workspaces &&
-									workspaces.length > 0 &&
-									checkedWorkspaces.length === workspaces.length
-								}
-								onCheckedChange={(checked) => {
-									if (!workspaces) {
-										return;
+						{isLoading ? (
+							<Skeleton className="h-4 w-40" />
+						) : (
+							<div
+								className={cn(
+									"flex items-center gap-5",
+									isEmpty && "invisible",
+								)}
+							>
+								<Checkbox
+									disabled={isEmpty}
+									checked={
+										!isEmpty && checkedWorkspaces.length === workspaces.length
 									}
-
-									if (!checked) {
-										onCheckChange([]);
-									} else {
-										onCheckChange(workspaces);
-									}
-								}}
-								aria-label="Select all workspaces"
-								className="my-0"
-							/>
-							Name
-						</div>
+									onCheckedChange={(checked) => {
+										if (!checked) {
+											onCheckChange([]);
+										} else {
+											onCheckChange(workspaces);
+										}
+									}}
+									aria-label="Select all workspaces"
+									className="my-0"
+								/>
+								Name
+							</div>
+						)}
+					</TableHead>
+					<TableHead className={cn("w-1/3", hideHeaders && "invisible")}>
+						Template
+					</TableHead>
+					<TableHead className={cn("w-1/3", hideHeaders && "invisible")}>
+						Status
 					</TableHead>
-					<TableHead className="w-1/3">Template</TableHead>
-					<TableHead className="w-1/3">Status</TableHead>
 					<TableHead className="w-0">
 						<span className="sr-only">Actions</span>
 					</TableHead>
 				</TableRow>
 			</TableHeader>
 			<TableBody className="[&_td]:h-[72px]">
-				{!workspaces && <TableLoader />}
-				{workspaces && workspaces.length === 0 && (
+				{isLoading && <TableLoader />}
+				{isEmpty && (
 					<TableRow>
 						<TableCell colSpan={999}>
 							<WorkspacesEmpty
@@ -198,7 +207,7 @@ export const WorkspacesTable: FC<WorkspacesTableProps> = ({
 									/>
 									<AvatarData
 										title={
-											<Stack direction="row" spacing={0.5} alignItems="center">
+											<div className="flex items-center gap-0.5">
 												<span className="whitespace-nowrap">
 													{workspace.name}
 												</span>
@@ -224,7 +233,7 @@ export const WorkspacesTable: FC<WorkspacesTableProps> = ({
 														</Link>
 													</Badge>
 												)}
-											</Stack>
+											</div>
 										}
 										subtitle={
 											<div className="flex items-center gap-1">
@@ -355,11 +364,11 @@ const TableLoader: FC = () => {
 					<AvatarDataSkeleton />
 				</TableCell>
 				<TableCell className="w-2/6">
-					<Skeleton variant="text" width="50%" />
+					<Skeleton className="h-4 w-1/2" />
 				</TableCell>
 				<TableCell className="w-0 ">
 					<div className="flex gap-1 justify-end">
-						<Skeleton variant="rounded" width={40} height={40} />
+						<Skeleton className="h-10 w-10" />
 						<Button size="icon-lg" variant="subtle" disabled>
 							<EllipsisVertical aria-hidden="true" />
 						</Button>