webui: Fix zero pasteLongTextToFileLen to disable conversion being overridden (#17445)

* webui: Fix zero pasteLongTextToFileLen to disable conversion being overridden

Zero pasteLongTextToFileLen should disable the conversion, but it was
overwritten with 2500.

* Apply suggestions from code review

* Update webui build

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

@@ -64,7 +64,10 @@
 	let fileInputRef: ChatFormFileInputInvisible | undefined = $state(undefined);
 	let isRecording = $state(false);
 	let message = $state('');
-	let pasteLongTextToFileLength = $derived(Number(currentConfig.pasteLongTextToFileLen) || 2500);
+	let pasteLongTextToFileLength = $derived.by(() => {
+		const n = Number(currentConfig.pasteLongTextToFileLen);
+		return Number.isNaN(n) ? 2500 : n;
+	});
 	let previousIsLoading = $state(isLoading);
 	let recordingSupported = $state(false);
 	let textareaRef: ChatFormTextarea | undefined = $state(undefined);