refactor(settings): reorganize FolderPicker component and update layout

- Moved FolderPicker to a new folder structure for better organization.
- Updated the Settings page layout to enhance visual hierarchy by increasing the title size.
- Removed the old FolderPicker component file after restructuring.

frontend/src/components/ImageViewer.tsx

@@ -1,7 +1,7 @@
-import { createEffect, createSignal } from "solid-js";
 import { listen } from "@tauri-apps/api/event";
-import { FolderPicker } from "./FolderPicker";
+import { createEffect, createSignal } from "solid-js";
 import { sendImage } from "../network";
+import { FolderPicker } from "./folder-picker/FolderPicker";
 
 export function ImageViewer() {
     const [latestImage, setLatestImage] = createSignal<string | null>(null);