feat: dodaj dodatne troškove s OCR sinkronizacijom

Dodana je tablica DODATNI TROŠKOVI za putni nalog (backend model + API +
frontend modal) s izračunom ukupnog iznosa za isplatu.

Upload računa sada odmah upisuje redak u dodatne troškove, a asinkroni OCR
(Celery) naknadno pokušava popuniti broj računa i iznos iz slike/PDF-a.

Uvedena je invalidacija PDF cache-a nakon promjena računa/dodatnih troškova
kako bi generirani PDF uvijek prikazivao najnovije podatke.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/modules/fleet/serializers.py

@@ -1,6 +1,7 @@
 from rest_framework import serializers
 import re
 from pathlib import Path
+from decimal import Decimal, InvalidOperation
 from django.urls import reverse
 from django.utils import timezone
 from .models import (
@@ -8,6 +9,7 @@ from .models import (
     Vehicle,
     VehicleNotification,
     WorkOrder,
+    WorkOrderAdditionalCostsTable,
     WorkOrderPhoto,
     WorkOrderInvoice,
     VehicleServiceRecord,
@@ -268,6 +270,61 @@ class WorkOrderInvoiceSerializer(serializers.ModelSerializer):
         return value
 
 
+class WorkOrderAdditionalCostsTableSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = WorkOrderAdditionalCostsTable
+        fields = ['id', 'work_order', 'data', 'total_for_payout', 'created_at', 'updated_at']
+        read_only_fields = ['id', 'total_for_payout', 'created_at', 'updated_at']
+
+    @staticmethod
+    def _parse_decimal(value):
+        if value in (None, ''):
+            return Decimal('0.00')
+        try:
+            normalized = str(value).strip().replace('€', '').replace(' ', '').replace(',', '.')
+            return Decimal(normalized)
+        except (InvalidOperation, ValueError, TypeError):
+            return Decimal('0.00')
+
+    def _normalize_row(self, row):
+        return {
+            'naziv': str(row.get('naziv', '') or '').strip(),
+            'broj_racuna': str(row.get('broj_racuna', '') or '').strip(),
+            'ukupan_iznos': str(row.get('ukupan_iznos', '') or '').strip(),
+            'prilog': str(row.get('prilog', '') or '').strip(),
+            'source_invoice_id': str(row.get('source_invoice_id', '') or '').strip(),
+        }
+
+    def validate_data(self, value):
+        if value is None:
+            return {'rows': []}
+        if not isinstance(value, dict):
+            raise serializers.ValidationError("Podaci tablice moraju biti JSON objekt.")
+        rows = value.get('rows', [])
+        if not isinstance(rows, list):
+            raise serializers.ValidationError({"rows": "Polje 'rows' mora biti lista redaka."})
+        normalized_rows = []
+        for row in rows[:100]:
+            if not isinstance(row, dict):
+                raise serializers.ValidationError({"rows": "Svaki redak mora biti JSON objekt."})
+            normalized_rows.append(self._normalize_row(row))
+        return {'rows': normalized_rows}
+
+    def _calculate_total_for_payout(self, data):
+        rows = data.get('rows', []) if isinstance(data, dict) else []
+        total = sum((self._parse_decimal(row.get('ukupan_iznos')) for row in rows), Decimal('0.00'))
+        return total.quantize(Decimal('0.01'))
+
+    def create(self, validated_data):
+        validated_data['total_for_payout'] = self._calculate_total_for_payout(validated_data.get('data'))
+        return super().create(validated_data)
+
+    def update(self, instance, validated_data):
+        data = validated_data.get('data', instance.data or {'rows': []})
+        validated_data['total_for_payout'] = self._calculate_total_for_payout(data)
+        return super().update(instance, validated_data)
+
+
 class WorkOrderPhotoSerializer(serializers.ModelSerializer):
     class Meta:
         model = WorkOrderPhoto