feat: add SlideAccordion component with expand/collapse functionality

src/once-ui/components/SlideAccordion.module.scss

@@ -0,0 +1,9 @@
+/* SlideAccordion.module.scss */
+.expandTransition {
+  transition: width 550ms cubic-bezier(0.33, 1, 0.68, 1), 
+              opacity 350ms ease-in-out;
+  will-change: width, opacity;
+  transform: translateZ(0);
+  backface-visibility: hidden;
+  perspective: 1000;
+}

src/once-ui/components/SlideAccordion.tsx

@@ -0,0 +1,151 @@
+"use client";
+
+import React, { useState } from "react";
+import { Flex, Text, Column, Icon, Background, Button } from ".";
+import styles from "./SlideAccordion.module.scss";
+import { FlexProps } from '../interfaces';
+
+export interface SlideAccordionItem {
+  title: string;
+  content: React.ReactNode;
+  buttonTitle: string;
+  icon: string;
+  background?: React.ComponentProps<typeof Background>;
+}
+
+interface SlideAccordionProps extends React.ComponentProps<typeof Flex> {
+  items: SlideAccordionItem[];
+  size?: "s" | "m" | "l";
+}
+
+const SlideAccordion: React.FC<SlideAccordionProps> = ({ items, size = "m", ...rest }) => {
+  const [hoveredIndex, setHoveredIndex] = useState<number | null>(null);
+
+  const collapsedWidth = size === "s" ? 5 : size === "m" ? 7 : 10; 
+
+  const expandedWidth = 20; 
+  const iconSize = size === "s" ? "xs" : size === "m" ? "s" : "m";
+
+  return (
+    <Flex direction="row" gap="8" overflowX="auto" padding="4" fillHeight>
+      {items.map((item, index) => {
+        const isExpanded = hoveredIndex === index;
+
+        return (
+          <Flex
+            key={index}
+            {...rest}
+            width={isExpanded ? expandedWidth : collapsedWidth}
+            background="surface"
+            fillHeight
+            border="neutral-alpha-medium"
+            radius="m"
+            cursor="pointer"
+            className={styles.expandTransition}
+            onMouseEnter={() => setHoveredIndex(index)}
+            onMouseLeave={() => setHoveredIndex(null)}
+            overflow="hidden"
+            position="relative"
+            style={{ 
+              transitionDelay: isExpanded ? '0ms' : '75ms' 
+            }}
+          >
+            {/* Background component when specified */}
+            {item.background && (
+              <Background {...item.background} position="absolute"/>
+            )}
+
+            {/* Collapsed view with vertical text and icon at bottom */}
+            <Flex 
+              direction="column"
+              fillWidth
+              fillHeight
+              vertical="space-between"
+              horizontal="center"
+              padding="16"
+              gap="12"
+              style={{
+                opacity: isExpanded ? 0 : 1,
+                position: "absolute",
+                inset: 0,
+                transition: "opacity 0.25s ease-out",
+                transitionDelay: isExpanded ? "0s" : "0.25s",
+                pointerEvents: isExpanded ? "none" : "auto",
+              }}
+            >
+              <Text 
+                variant={`heading-strong-${size === "s" ? "xs" : "s"}`}
+                style={{
+                  writingMode: "vertical-lr",
+                  transform: "rotate(180deg)",
+                  textOrientation: "mixed"
+                }}
+              >
+                {item.title}
+              </Text>
+
+              <Icon 
+                name={item.icon} 
+                size={iconSize} 
+                onBackground="neutral-strong" 
+              />
+            </Flex>
+
+            {/* Expanded view with full content */}
+            <Flex
+              direction="column"
+              fillWidth
+              vertical="space-between"
+              fillHeight
+              padding="24"
+              gap="16"
+              style={{
+                opacity: isExpanded ? 1 : 0,
+                position: "absolute",
+                inset: 0,
+                transition: "opacity 0.25s ease-in",
+                transitionDelay: isExpanded ? "0.25s" : "0s",
+                pointerEvents: isExpanded ? "auto" : "none",
+              }}
+            >
+              <Flex horizontal="space-between" vertical="center">
+                <Text variant={`heading-strong-${size === "l" ? "m" : "s"}`}>
+                  {item.title}
+                </Text>
+                <Icon 
+                  name={item.icon} 
+                  size={iconSize} 
+                  onBackground="neutral-strong" 
+                />
+              </Flex>
+
+              <Column 
+                gap="12" 
+                overflow="auto"
+                style={{
+                  opacity: isExpanded ? 1 : 0,
+                  transform: isExpanded ? "translateX(0)" : "translateX(20px)",
+                  transition: "opacity 0.3s ease, transform 0.3s ease",
+                  transitionDelay: isExpanded ? "0.35s" : "0s",
+                }}
+              >
+                <Text 
+                  variant={`body-default-${size === "s" ? "xs" : "s"}`} 
+                  onBackground="neutral-weak"
+                >
+                  {item.content}
+                </Text>
+                <Button variant="secondary">
+                  {item.buttonTitle}
+                </Button>
+              </Column>
+            </Flex>
+          </Flex>
+        );
+      })}
+    </Flex>
+  );
+};
+
+SlideAccordion.displayName = "SlideAccordion";
+export { SlideAccordion };

src/once-ui/components/index.ts

@@ -55,6 +55,7 @@ export * from "./Select";
 export * from "./Skeleton";
 export * from "./SmartImage";
 export * from "./SmartLink";
+export * from "./SlideAccordion";
 export * from "./Spinner";
 export * from "./StatusIndicator";
 export * from "./StylePanel";