feat(UI): Adding a session manager (#3203)

# What does this PR do?

- Introduces the Agent Session creation for the Playground and allows
users to set tools
- note tools are actually not usable yet and this is marked explicitly
- this also caches sessions locally for faster loading on the UI and
deletes them appropriately
   - allows users to easily create new sessions as well
- Moved Model Configuration settings and "System Message" / Prompt to
the left component
- Added new logo and favicon
- Added new typing animation when LLM is generating

### Create New Session
<img width="1916" height="1393" alt="Screenshot 2025-08-21 at 4 18
08 PM"
src="https://github.com/user-attachments/assets/52c70ae3-a33e-4338-8522-8184c692c320"
/>


### List of Sessions
<img width="1920" height="1391" alt="Screenshot 2025-08-21 at 4 18
56 PM"
src="https://github.com/user-attachments/assets/ed78c3c6-08ec-486c-8bad-9b7382c11360"
/>

<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->

## Test Plan
Unit tests added

---------

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

llama_stack/ui/components/layout/app-sidebar.tsx

@@ -11,6 +11,7 @@ import {
 } from "lucide-react";
 import Link from "next/link";
 import { usePathname } from "next/navigation";
+import Image from "next/image";
 import { cn } from "@/lib/utils";
 
 import {
@@ -110,7 +111,16 @@ export function AppSidebar() {
   return (
     <Sidebar>
       <SidebarHeader>
-        <Link href="/">Llama Stack</Link>
+        <Link href="/" className="flex items-center gap-2 p-2">
+          <Image
+            src="/logo.webp"
+            alt="Llama Stack"
+            width={32}
+            height={32}
+            className="h-8 w-8"
+          />
+          <span className="font-semibold text-lg">Llama Stack</span>
+        </Link>
       </SidebarHeader>
       <SidebarContent>
         <SidebarGroup>