Serve the styleguide's images and links locally

The styleguide loaded 42 images from picsum.photos and linked demo items to
daisyui.com. It now uses six small SVG landscapes in wwwroot/imgs/styleguide/
(the diff demo greys one with the grayscale utility), and its demo links stay on
/styleguide.

It also gains a carousel demo with navigation and indicators.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

Components/Styleguide/LayoutSection.razor

@@ -101,7 +101,7 @@
 				<DButton Color="DColor.Primary">Get started</DButton>
 			</div>
 		</DHero>
-		<DHero BackgroundImage="https://picsum.photos/seed/hero/800/400" Overlay="true" class="min-h-64 rounded-box overflow-hidden"
+		<DHero BackgroundImage="imgs/styleguide/scene-5.svg" Overlay="true" class="min-h-64 rounded-box overflow-hidden"
 			   ContentClass="text-neutral-content text-center">
 			<div class="max-w-md">
 				<h1 class="text-3xl font-bold">With an overlay</h1>
@@ -109,7 +109,7 @@
 			</div>
 		</DHero>
 		<DHero class="rounded-box bg-base-200" ContentClass="flex-col lg:flex-row">
-			<img src="https://picsum.photos/seed/figure/200/260" class="max-w-32 rounded-lg shadow-2xl" alt="" />
+			<img src="imgs/styleguide/scene-1.svg" class="max-w-32 rounded-lg shadow-2xl" alt="" />
 			<div>
 				<h1 class="text-2xl font-bold">With a figure</h1>
 				<p class="py-2">Column on small screens, row from lg up.</p>
@@ -180,7 +180,7 @@
 			@foreach (var shape in Enum.GetValues<DMaskShape>().Skip(1))
 			{
 				<div class="flex flex-col items-center gap-1 text-xs">
-					<DMask Shape="shape" Src="https://picsum.photos/seed/mask/160/160" alt="@shape" class="h-16 w-16" />
+					<DMask Shape="shape" Src="imgs/styleguide/scene-3.svg" alt="@shape" class="h-16 w-16" />
 					@shape
 				</div>
 			}
@@ -207,9 +207,9 @@
 				</div>
 			}
 			<DStack class="w-32">
-				<img src="https://picsum.photos/seed/stack1/200/140" class="rounded-box" alt="" />
-				<img src="https://picsum.photos/seed/stack2/200/140" class="rounded-box" alt="" />
-				<img src="https://picsum.photos/seed/stack3/200/140" class="rounded-box" alt="" />
+				<img src="imgs/styleguide/scene-2.svg" class="rounded-box" alt="" />
+				<img src="imgs/styleguide/scene-3.svg" class="rounded-box" alt="" />
+				<img src="imgs/styleguide/scene-4.svg" class="rounded-box" alt="" />
 			</DStack>
 		</div>
 	</section>