feat: add link to skills on create-a-template page (#24710)

This pull request updates the `CreateTemplateGalleryPageView` component
to enhance the page header actions by grouping them vertically and
adding a new external link button for users. The most important changes
are:

**UI improvements:**

* Groups the header action buttons into a vertical stack using a flex
container with column direction and spacing for better layout and
accessibility.

**New feature:**

* Adds a new button linking to the "template agent skill" documentation
on GitHub, allowing users to easily access guidance on using the
template agent skill.

**Screenshot**

<img width="1674" height="813" alt="image"
src="https://github.com/user-attachments/assets/8d12df13-2310-464b-936c-1b4e2215c7aa"
/>

site/src/pages/CreateTemplateGalleryPage/CreateTemplateGalleryPageView.tsx

@@ -30,17 +30,30 @@ export const CreateTemplateGalleryPageView: FC<
 		<Margins className="pb-12">
 			<PageHeader
 				actions={
-					<Button asChild size="sm" variant="outline">
-						<a
-							href="https://registry.coder.com/templates"
-							target="_blank"
-							rel="noopener noreferrer"
-							className="flex items-center"
-						>
-							Browse other Templates on the Coder Registry
-							<ExternalLinkIcon className="size-icon-sm ml-1" />
-						</a>
-					</Button>
+					<div className="flex flex-col items-end gap-2">
+						<Button asChild size="sm" variant="outline">
+							<a
+								href="https://registry.coder.com/templates"
+								target="_blank"
+								rel="noopener noreferrer"
+								className="flex items-center"
+							>
+								Browse other Templates on the Coder Registry
+								<ExternalLinkIcon className="size-icon-sm ml-1" />
+							</a>
+						</Button>
+						<Button asChild size="sm" variant="outline">
+							<a
+								href="https://registry.coder.com/skills/coder-templates"
+								target="_blank"
+								rel="noopener noreferrer"
+								className="flex items-center"
+							>
+								Use our template agent skill
+								<ExternalLinkIcon className="size-icon-sm ml-1" />
+							</a>
+						</Button>
+					</div>
 				}
 			>
 				<PageHeaderTitle>Create a Template</PageHeaderTitle>

site/src/pages/TemplatePage/TemplateFilesPage/TemplateFilesPage.tsx

@@ -65,7 +65,7 @@ const TemplateFilesPage: FC = () => {
 					<div className="flex items-center gap-2 mt-4">
 						<Button asChild size="sm" variant="default">
 							<a
-								href="https://github.com/coder/registry/blob/main/.agents/skills/coder-templates/SKILL.md"
+								href="https://registry.coder.com/skills/coder-templates"
 								target="_blank"
 								rel="noopener noreferrer"
 								className="flex items-center"