chore(site): remove outdated featured empty-state images (#28454)

> 🤖 This PR was written by Coder Agents on behalf of Jake Howell.

## What

The images in `site/static/featured` were outdated and no longer
resembled the current UI, so this removes them along with the code that
referenced them:

- `workspaces.webp` — was the faded background image in the Workspaces
empty state (`WorkspacesEmpty.tsx`).
- `templates.webp` — was only referenced by a Storybook story
(`TableEmpty.stories.tsx`).
- `scheduling.webp` — had no references anywhere in the codebase.

### Cleanup alongside the removal

- Dropped the `image={defaultImage}` prop (and the now-dead
`defaultImage`) from all three `WorkspacesEmpty` states.
- Removed the `className="pb-0"` / `paddingBottom: 0` overrides that
only existed to seat the image flush against the bottom, restoring
balanced padding.
- Renamed the `TableEmpty` story `WithImageAndCta` → `WithCta` since it
no longer has an image.

## Old | New

| Surface | Old | New |
|---|---|---|
| Workspaces empty state | <img width="2306" height="1376"
alt="main-tableempty"
src="https://github.com/user-attachments/assets/1d3a5201-66ce-4f80-a2ea-5638221f95d0"
/> | <img width="2306" height="1376" alt="pr-tableempty"
src="https://github.com/user-attachments/assets/5a8fcc1d-b676-46e6-be54-12ff7f3489fd"
/> |
| Table empty state (templates) | <img width="2306" height="1376"
alt="main-workspaces-empty"
src="https://github.com/user-attachments/assets/7618ee1f-09d4-4398-8a1c-19362f63c80d"
/> | <img width="2306" height="1376" alt="pr-workspaces-empty"
src="https://github.com/user-attachments/assets/8a9c98a9-24b7-4c90-9959-f85dbc2daa9f"
/> |
| `scheduling.webp` | Unused | Deleted 🙂  |
<details>
<summary>Implementation notes / decision log</summary>

- Verified references with a repo-wide search for `/featured/` and each
`*.webp` filename. Only `WorkspacesEmpty.tsx` (real usage) and
`TableEmpty.stories.tsx` (Storybook-only) referenced them;
`scheduling.webp` was fully unused.
- `EmptyState`'s `image` prop is optional, so removing usages required
no component changes.
- Delete-only (per request): no replacement images committed. The empty
states now render as clean text/CTA layouts.
- "New" screenshots were captured from Storybook (a temporary
`WorkspacesEmpty` story was used only to render the states and was
**not** committed).
- Verified with `tsc --noEmit` (0 errors) and `biome check` (clean) on
the changed files.

</details>

site/src/components/TableEmpty/TableEmpty.stories.tsx

@@ -25,8 +25,8 @@ type Story = StoryObj<typeof TableEmpty>;
 
 export const Example: Story = {};
 
-export const WithImageAndCta: Story = {
-	name: "With Image and CTA",
+export const WithCta: Story = {
+	name: "With CTA",
 	args: {
 		description: "A gruff voice crackles to life on the intercom.",
 		cta: (
@@ -35,13 +35,5 @@ export const WithImageAndCta: Story = {
 				code="say &ldquo;Actually, it's the BBC controlling us from London&rdquo;"
 			/>
 		),
-		image: (
-			<img
-				src="/featured/templates.webp"
-				alt=""
-				className="max-w-3xl h-[320px] overflow-hidden object-cover object-top"
-			/>
-		),
-		style: { paddingBottom: 0 },
 	},
 };

site/src/pages/WorkspacesPage/WorkspacesEmpty.tsx

@@ -26,11 +26,6 @@ export const WorkspacesEmpty: FC<WorkspacesEmptyProps> = ({
 	const defaultTitle = "Create a workspace";
 	const defaultMessage =
 		"A workspace is your personal, customizable development environment.";
-	const defaultImage = (
-		<div className="max-w-[50%] h-[272px] overflow-hidden mt-12 opacity-85">
-			<img src="/featured/workspaces.webp" alt="" className="max-w-full" />
-		</div>
-	);
 
 	if (isUsingFilter) {
 		return <EmptyState message="No results matched your search" />;
@@ -41,8 +36,6 @@ export const WorkspacesEmpty: FC<WorkspacesEmptyProps> = ({
 			<EmptyState
 				message="No workspaces"
 				description="You don't have permission to create workspaces. Contact your administrator if you need workspace access."
-				className="pb-0"
-				image={defaultImage}
 			/>
 		);
 	}
@@ -57,8 +50,6 @@ export const WorkspacesEmpty: FC<WorkspacesEmptyProps> = ({
 						<Link to="/templates/new/builder">Create a template</Link>
 					</Button>
 				}
-				className="pb-0"
-				image={defaultImage}
 			/>
 		);
 	}
@@ -68,8 +59,6 @@ export const WorkspacesEmpty: FC<WorkspacesEmptyProps> = ({
 			<EmptyState
 				message={defaultTitle}
 				description={`${defaultMessage} There are no templates available, but you will see them here once your admin adds them.`}
-				className="pb-0"
-				image={defaultImage}
 			/>
 		);
 	}