refactor: use date-fns for dashboard dates

package.json

@@ -65,5 +65,8 @@
 		"vite": "^8.0.7",
 		"wrangler": "^4.81.0",
 		"zod": "^4.4.3"
+	},
+	"dependencies": {
+		"date-fns": "^4.4.0"
 	}
 }

pnpm-lock.yaml

@@ -7,6 +7,10 @@ settings:
 importers:
 
   .:
+    dependencies:
+      date-fns:
+        specifier: ^4.4.0
+        version: 4.4.0
     devDependencies:
       '@better-auth/cli':
         specifier: ~1.4.21
@@ -2213,6 +2217,9 @@ packages:
     resolution: {integrity: sha512-G7gHKj89n2owmkGb6WX6ixcnQ0Kf/0wpa9VIh9DGdbHu8wdrlaHU4ir3/bFNERl8N8nn4G7e7qbtBG8N9caihQ==}
     engines: {node: '>=12'}
 
+  date-fns@4.4.0:
+    resolution: {integrity: sha512-+1UMbeh68lH1SegH83CGWwpb6OHHbpSgr3+s5Eww5M4CAgswBpoWS0AjTOfEJ33HiYKz1hdj/KTFprzXHmq/6w==}
+
   dayjs@1.11.20:
     resolution: {integrity: sha512-YbwwqR/uYpeoP4pu043q+LTDLFBLApUP6VxRihdfNTqu4ubqMlGDLd6ErXhEgsyvY0K6nCs7nggYumAN+9uEuQ==}
 
@@ -5521,6 +5528,8 @@ snapshots:
       d3-delaunay: 6.0.4
       d3-scale: 4.0.2
 
+  date-fns@4.4.0: {}
+
   dayjs@1.11.20:
     optional: true
 

src/routes/dashboard/+page.server.ts

@@ -1,3 +1,4 @@
+import { addDays, addMonths, endOfMonth, format, parseISO, startOfMonth } from 'date-fns';
 import { and, asc, count, desc, eq, gte, inArray, isNull, lt, lte, ne, sql } from 'drizzle-orm';
 import { db } from '$lib/server/db';
 import {
@@ -12,42 +13,20 @@ import {
 import { loadOrganizationContext } from '$lib/server/organizations';
 import type { PageServerLoad } from './$types';
 
-const dayMs = 24 * 60 * 60 * 1000;
-
-function pad(value: number) {
-	return String(value).padStart(2, '0');
-}
-
 function dateOnly(date: Date) {
-	return `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}`;
+	return format(date, 'yyyy-MM-dd');
 }
 
 function dateTimeLocal(date: Date) {
-	return `${dateOnly(date)}T${pad(date.getHours())}:${pad(date.getMinutes())}`;
-}
-
-function startOfMonth(date: Date) {
-	return new Date(date.getFullYear(), date.getMonth(), 1);
-}
-
-function endOfMonth(date: Date) {
-	return new Date(date.getFullYear(), date.getMonth() + 1, 0);
-}
-
-function addDays(date: Date, days: number) {
-	return new Date(date.getTime() + days * dayMs);
-}
-
-function addMonths(date: Date, months: number) {
-	return new Date(date.getFullYear(), date.getMonth() + months, 1);
+	return format(date, "yyyy-MM-dd'T'HH:mm");
 }
 
 function monthKey(date: Date) {
-	return `${date.getFullYear()}-${pad(date.getMonth() + 1)}`;
+	return format(date, 'yyyy-MM');
 }
 
 function monthLabel(date: Date) {
-	return new Intl.DateTimeFormat('en-GB', { month: 'short', year: 'numeric' }).format(date);
+	return format(date, 'MMM yyyy');
 }
 
 function roomTypeLabel(type: string) {
@@ -323,7 +302,7 @@ export const load: PageServerLoad = async ({ locals }) => {
 		});
 	}
 	for (const invoice of billingTrendInvoiceRows) {
-		const issuedAt = new Date(`${invoice.issueDate}T00:00:00`);
+		const issuedAt = parseISO(invoice.issueDate);
 		const key = monthKey(issuedAt);
 		const existing = billingTrendMap.get(key);
 		if (!existing) continue;