Use MutationObserver to constrain dynamically-rendered date inputs

Previous afterNavigate hook missed inputs inside conditional blocks
that appear after user interaction (e.g. the "+ New Expense" form).
Replaced with a MutationObserver on document.body that catches every
<input type="date"> as it's added to the DOM and sets min/max.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routes/+layout.svelte

@@ -1,23 +1,34 @@
 <script lang="ts">
 	import '../app.css';
-	import { afterNavigate } from '$app/navigation';
 	import { onMount } from 'svelte';
 
 	let { children } = $props();
 
-	// Constrain date inputs so browsers don't render yyyyyy-mm-dd
-	function constrainDateInputs() {
-		document.querySelectorAll<HTMLInputElement>('input[type="date"]').forEach((el) => {
-			if (!el.hasAttribute('min')) el.setAttribute('min', '1900-01-01');
-			if (!el.hasAttribute('max')) el.setAttribute('max', '2100-12-31');
-		});
+	// Constrain date inputs so browsers don't render yyyyyy-mm-dd.
+	// Uses a MutationObserver so dynamically-rendered inputs get constrained too.
+	function constrainEl(el: Element) {
+		if (!(el instanceof HTMLInputElement)) return;
+		if (el.type !== 'date') return;
+		if (!el.hasAttribute('min')) el.setAttribute('min', '1900-01-01');
+		if (!el.hasAttribute('max')) el.setAttribute('max', '2100-12-31');
+	}
+	function constrainRoot(root: ParentNode) {
+		root.querySelectorAll<HTMLInputElement>('input[type="date"]').forEach(constrainEl);
 	}
 
 	onMount(() => {
-		constrainDateInputs();
-	});
-	afterNavigate(() => {
-		queueMicrotask(constrainDateInputs);
+		constrainRoot(document);
+		const observer = new MutationObserver((mutations) => {
+			for (const m of mutations) {
+				for (const node of m.addedNodes) {
+					if (node.nodeType !== 1) continue;
+					constrainEl(node as Element);
+					if ((node as Element).querySelectorAll) constrainRoot(node as Element);
+				}
+			}
+		});
+		observer.observe(document.body, { childList: true, subtree: true });
+		return () => observer.disconnect();
 	});
 </script>