Fix queue scheduled time displayed in wrong timezone

When editing a queue item, the scheduled time was being displayed in UTC
instead of the user's local timezone. This caused confusion where:
- User selects April 2, 2:00 PM local time
- After saving, it appears shifted by their timezone offset
- Month/day could appear swapped due to the timezone difference

The fix converts the UTC time from the server to local time when
populating the datetime-local input, using toDateTimeLocalValue()
instead of toISOString().slice(0, 16).

Closes #233

CHANGELOG.md

@@ -15,6 +15,9 @@ All notable changes to Bambuddy will be documented in this file.
   - Queue now shows "Paused" when the printer is paused instead of "Printing"
   - Fetches real-time printer state for actively printing queue items
   - Added translations for paused status in English, German, and Japanese
+- **Queue Scheduled Time Displayed in Wrong Timezone** (Issue #233):
+  - Fixed scheduled time being displayed in UTC instead of local timezone when editing queue items
+  - The datetime picker now correctly shows and saves times in the user's local timezone
 
 ### Added
 - **Windows Portable Launcher** (contributed by nmori):

frontend/src/components/PrintModal/index.tsx

@@ -10,6 +10,7 @@ import { useToast } from '../../contexts/ToastContext';
 import { useFilamentMapping } from '../../hooks/useFilamentMapping';
 import { useMultiPrinterFilamentMapping, type PerPrinterConfig } from '../../hooks/useMultiPrinterFilamentMapping';
 import { isPlaceholderDate } from '../../utils/amsHelpers';
+import { toDateTimeLocalValue } from '../../utils/date';
 import { PrinterSelector } from './PrinterSelector';
 import { PlateSelector } from './PlateSelector';
 import { FilamentMapping } from './FilamentMapping';
@@ -90,7 +91,8 @@ export function PrintModal({
       let scheduledTime = '';
       if (queueItem.scheduled_time && !isPlaceholderDate(queueItem.scheduled_time)) {
         const date = new Date(queueItem.scheduled_time);
-        scheduledTime = date.toISOString().slice(0, 16);
+        // Use toDateTimeLocalValue to convert UTC to local time for datetime-local input
+        scheduledTime = toDateTimeLocalValue(date);
       }
 
       return {

static/index.html

@@ -23,7 +23,7 @@
 
     <!-- Splash screens for iOS -->
     <link rel="apple-touch-startup-image" href="/img/android-chrome-512x512.png" />
-    <script type="module" crossorigin src="/assets/index-C32ywEzV.js"></script>
+    <script type="module" crossorigin src="/assets/index-C8HAsISy.js"></script>
     <link rel="stylesheet" crossorigin href="/assets/index-fdAEMOwp.css">
   </head>
   <body>