🔄 refactor: Migrate to react-resizable-panels v4 with Artifacts Header polish (#12356)

* chore: Update react-resizable-panels dependency to version 4.7.4

- Upgraded the "react-resizable-panels" package in package-lock.json, package.json, and client package.json files to ensure compatibility with the latest features and improvements.
- Adjusted peer dependencies for React and ReactDOM to align with the new version requirements.

* refactor: Update Share and SidePanel components to `react-resizable-panels` v4

- Refactored the ShareArtifactsContainer to utilize a new layout change handler, enhancing artifact panel resizing functionality.
- Updated ArtifactsPanel to use the new `usePanelRef` hook, improving panel reference management.
- Simplified SidePanelGroup by removing unnecessary layout normalization and integrating default layout handling with localStorage.
- Removed the deprecated `normalizeLayout` utility function to streamline the codebase.
- Adjusted Resizable components to ensure consistent sizing and layout behavior across panels.

* style: Enhance scrollbar appearance across application

- Added custom scrollbar styles to both artifacts and markdown files, improving aesthetics and user experience.
- Implemented dark mode adjustments for scrollbar visibility, ensuring consistency across different color schemes.

* style: Standardize button sizes and layout in Artifacts components

- Updated button dimensions to a consistent height of 9 units across various components including Artifacts, Code, and DownloadArtifact.
- Adjusted padding and layout properties in the Artifacts header for improved visual consistency.
- Enhanced the Radio component to accept a new `buttonClassName` prop for better customization of button styles.

* chore: import order

package-lock.json

@@ -461,7 +461,7 @@
         "react-hook-form": "^7.43.9",
         "react-i18next": "^15.4.0",
         "react-markdown": "^9.0.1",
-        "react-resizable-panels": "^3.0.6",
+        "react-resizable-panels": "^4.7.4",
         "react-router-dom": "^6.30.3",
         "react-speech-recognition": "^3.10.0",
         "react-textarea-autosize": "^8.4.0",
@@ -38086,13 +38086,13 @@
       }
     },
     "node_modules/react-resizable-panels": {
-      "version": "3.0.6",
-      "resolved": "https://registry.npmjs.org/react-resizable-panels/-/react-resizable-panels-3.0.6.tgz",
-      "integrity": "sha512-b3qKHQ3MLqOgSS+FRYKapNkJZf5EQzuf6+RLiq1/IlTHw99YrZ2NJZLk4hQIzTnnIkRg2LUqyVinu6YWWpUYew==",
+      "version": "4.7.4",
+      "resolved": "https://registry.npmjs.org/react-resizable-panels/-/react-resizable-panels-4.7.4.tgz",
+      "integrity": "sha512-1sehMbUJxZFj4imu1TuH+RS7Xe5Jo+3HyxBYafCEdxPmDeLAQNmKEByyxCQRl7xCLa5cLXSJ9T8acQyyiPsNdQ==",
       "license": "MIT",
       "peerDependencies": {
-        "react": "^16.14.0 || ^17.0.0 || ^18.0.0 || ^19.0.0 || ^19.0.0-rc",
-        "react-dom": "^16.14.0 || ^17.0.0 || ^18.0.0 || ^19.0.0 || ^19.0.0-rc"
+        "react": "^18.0.0 || ^19.0.0",
+        "react-dom": "^18.0.0 || ^19.0.0"
       }
     },
     "node_modules/react-router": {
@@ -44131,7 +44131,7 @@
         "react-dom": "^18.2.0 || ^19.1.0",
         "react-hook-form": "^7.56.4",
         "react-i18next": "^15.4.0 || ^15.6.0",
-        "react-resizable-panels": "^3.0.6",
+        "react-resizable-panels": "^4.7.4",
         "react-textarea-autosize": "^8.4.0",
         "tailwind-merge": "^1.9.1"
       }