feat: Sets focus to ChatForm's <textarea> after load

Sets the focus to the textarea element when the component
mounts and after the loading state changes from true to false.

This improves user experience by automatically placing the cursor
in the input field, allowing users to start typing immediately.

Author: allozaur

tools/server/webui/src/lib/components/chat/ChatForm.svelte

@@ -5,6 +5,7 @@
 	import type { ChatUploadedFile } from '$lib/types/chat.d.ts';
 	import { ChatAttachmentsList } from '$lib/components';
 	import { inputClasses } from '$lib/constants/input-classes';
+	import { onMount } from 'svelte';
 
 	interface Props {
 		class?: string;
@@ -35,6 +36,21 @@
 	let message = $state('');
 	let textareaElement: HTMLTextAreaElement | undefined;
 	let fileInputElement: HTMLInputElement | undefined;
+	let previousIsLoading = $state(isLoading);
+
+	onMount(() => {
+		if (textareaElement) {
+			textareaElement.focus();
+		}
+	});
+
+	$effect(() => {
+		if (previousIsLoading && !isLoading && textareaElement) {
+			textareaElement.focus();
+		}
+
+		previousIsLoading = isLoading;
+	});
 
 	async function handleSubmit(event: SubmitEvent) {
 		event.preventDefault();