fix: replace toISOString date conversion in OCR parser with local time formatting (refs #237)

The parseServiceDate function used toISOString().split('T')[0] which converts
to UTC, shifting dates by one day depending on timezone. Standard parsing now
uses getFullYear/getMonth/getDate (local time). MM/DD/YYYY parsing now formats
directly from regex groups without round-tripping through a Date object.

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

frontend/src/features/maintenance/hooks/useMaintenanceReceiptOcr.ts

@@ -107,17 +107,17 @@ function parseServiceDate(value: string | number | null): string | undefined {
   // Try standard parsing
   const date = new Date(dateStr);
   if (!isNaN(date.getTime())) {
-    return date.toISOString().split('T')[0];
+    const y = date.getFullYear();
+    const m = String(date.getMonth() + 1).padStart(2, '0');
+    const d = String(date.getDate()).padStart(2, '0');
+    return `${y}-${m}-${d}`;
   }
 
   // Try MM/DD/YYYY format
   const mdyMatch = dateStr.match(/(\d{1,2})\/(\d{1,2})\/(\d{4})/);
   if (mdyMatch) {
     const [, month, day, year] = mdyMatch;
-    const parsed = new Date(parseInt(year), parseInt(month) - 1, parseInt(day));
-    if (!isNaN(parsed.getTime())) {
-      return parsed.toISOString().split('T')[0];
-    }
+    return `${year}-${month.padStart(2, '0')}-${day.padStart(2, '0')}`;
   }
 
   return undefined;