feat: Adding dark mode, cleaning the UI a small bit, adding a link to the API documentation, and linting the code. (#2182)

# What does this PR do?

This PR adds a few enhancements:
- Dark mode 
- A dark mode icon
- Adds a link to the API documentation
- Adds prettier and a linter to the code 
- Aligning the default text
- Linted the code 

## Before:
![Screenshot 2025-05-15 at 3 57
15 PM](https://github.com/user-attachments/assets/996db083-4a4f-4683-a2b4-e7c09de96135)

## After (dark mode):
![Screenshot 2025-05-15 at 3 57
50 PM](https://github.com/user-attachments/assets/9d45d26b-2449-4a5f-813e-29e07e94b793)

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
[Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.*]

[//]: # (## Documentation)


Related to https://github.com/meta-llama/llama-stack/issues/2085

---------

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

llama_stack/ui/components/ui/mode-toggle.tsx

@@ -0,0 +1,40 @@
+"use client";
+
+import * as React from "react";
+import { Moon, Sun } from "lucide-react";
+import { useTheme } from "next-themes";
+
+import { Button } from "@/components/ui/button";
+import {
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuItem,
+  DropdownMenuTrigger,
+} from "@/components/ui/dropdown-menu";
+
+export function ModeToggle() {
+  const { setTheme } = useTheme();
+
+  return (
+    <DropdownMenu>
+      <DropdownMenuTrigger asChild>
+        <Button variant="outline" size="icon">
+          <Sun className="h-[1.2rem] w-[1.2rem] rotate-0 scale-100 transition-all dark:-rotate-90 dark:scale-0" />
+          <Moon className="absolute h-[1.2rem] w-[1.2rem] rotate-90 scale-0 transition-all dark:rotate-0 dark:scale-100" />
+          <span className="sr-only">Toggle theme</span>
+        </Button>
+      </DropdownMenuTrigger>
+      <DropdownMenuContent align="end">
+        <DropdownMenuItem onClick={() => setTheme("light")}>
+          Light
+        </DropdownMenuItem>
+        <DropdownMenuItem onClick={() => setTheme("dark")}>
+          Dark
+        </DropdownMenuItem>
+        <DropdownMenuItem onClick={() => setTheme("system")}>
+          System
+        </DropdownMenuItem>
+      </DropdownMenuContent>
+    </DropdownMenu>
+  );
+}