feat(docs): migrate and reorganize frontend guides for BP panel and file uploads

- Deleted outdated documentation files for BP panel list sorting and Filestore frontend guide.
- Created new documentation files for BP panel list sorting and Filestore frontend guide in the client directory.
- Updated the structure and content to enhance clarity and accessibility for frontend integration with file upload and profile image APIs.
- Ensured consistency in documentation style and improved examples for better developer experience.

next.config.mjs

@@ -26,6 +26,11 @@ const nextConfig = {
         hostname: "pub-b7fd9c30cdbf439183b75041f5f71b92.r2.dev",
         port: "",
       },
+      {
+        protocol: "https",
+        hostname: "admin.opplenz.com",
+        port: "",
+      },
     ],
   },
   async rewrites() {