feat: add sliding container chat view with session management

- Add sliding container component for playground panel
- Integrate chat header with session rename, delete, and message logs
- Add session sidebar in fullscreen mode
- Implement session fetching and management
- Add rename functionality with optimistic updates
- Fix sessionStorage JSON parsing bug in use-rename-session and use-put-update-messages
- Comment out IOModal to test sliding container (will be reverted before merge)
- Add basic tests for sliding container components

src/frontend/src/components/core/flowToolbarComponent/components/playground-button.tsx

@@ -1,7 +1,9 @@
 import ForwardedIconComponent from "@/components/common/genericIconComponent";
 import ShadTooltip from "@/components/common/shadTooltipComponent";
 import { PLAYGROUND_BUTTON_NAME } from "@/constants/constants";
-import { CustomIOModal } from "@/customization/components/custom-new-modal";
+import { PlaygroundButtonSliding } from "@/customization/components/custom-playground-button-sliding";
+// Will be reverted before merging this PR - IOModal commented out to test sliding container
+// import { CustomIOModal } from "@/customization/components/custom-new-modal";
 import { ENABLE_PUBLISH } from "@/customization/feature-flags";
 
 interface PlaygroundButtonProps {
@@ -49,22 +51,26 @@ const PlaygroundButton = ({
   setOpen,
   canvasOpen,
 }: PlaygroundButtonProps) => {
-  return hasIO ? (
-    <CustomIOModal
-      open={open}
-      setOpen={setOpen}
-      disable={!hasIO}
-      canvasOpen={canvasOpen}
-    >
-      <ActiveButton />
-    </CustomIOModal>
-  ) : (
-    <ShadTooltip content="Add a Chat Input or Chat Output to use the playground">
-      <div>
-        <DisabledButton />
-      </div>
-    </ShadTooltip>
-  );
+  // Will be reverted before merging this PR - IOModal commented out to test sliding container
+  // return hasIO ? (
+  //   <CustomIOModal
+  //     open={open}
+  //     setOpen={setOpen}
+  //     disable={!hasIO}
+  //     canvasOpen={canvasOpen}
+  //   >
+  //     <ActiveButton />
+  //   </CustomIOModal>
+  // ) : (
+  //   <ShadTooltip content="Add a Chat Input or Chat Output to use the playground">
+  //     <div>
+  //       <DisabledButton />
+  //     </div>
+  //   </ShadTooltip>
+  // );
+
+  // New sliding container implementation for testing
+  return <PlaygroundButtonSliding hasIO={hasIO} />;
 };
 
 export default PlaygroundButton;

src/frontend/src/components/core/playgroundComponent/chat-view/chat-header/components/chat-header-actions.tsx

@@ -0,0 +1,22 @@
+import React from "react";
+import ForwardedIconComponent from "@/components/common/genericIconComponent";
+
+interface ChatHeaderActionsProps {
+  onNewChat?: () => void;
+}
+
+export function ChatHeaderActions({ onNewChat }: ChatHeaderActionsProps) {
+  if (!onNewChat) return null;
+
+  return (
+    <div className="flex items-center gap-2">
+      <button
+        onClick={onNewChat}
+        className="p-2 hover:bg-accent rounded transition-colors"
+        aria-label="New chat"
+      >
+        <ForwardedIconComponent name="Plus" className="h-4 w-4" />
+      </button>
+    </div>
+  );
+}