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/migrations/0029_alter_workorder_purpose.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.2.15 on 2026-07-19 17:54
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fleet', '0028_alter_workorderinvoice_image'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='workorder',
+            name='purpose',
+            field=models.CharField(blank=True, choices=[('defektaza', 'Defektaža'), ('kontrola', 'Kontrola'), ('redovni_pregled', 'Redovni pregled'), ('popravak', 'Popravak')], max_length=50, verbose_name='Svrha'),
+        ),
+    ]

backend/modules/fleet/migrations/0029_workorderadditionalcoststable.py

@@ -0,0 +1,31 @@
+from decimal import Decimal
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fleet', '0028_alter_workorderinvoice_image'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='WorkOrderAdditionalCostsTable',
+            fields=[
+                ('id', models.UUIDField(editable=False, primary_key=True, serialize=False)),
+                ('created_at', models.DateTimeField(auto_now_add=True)),
+                ('updated_at', models.DateTimeField(auto_now=True)),
+                ('is_active', models.BooleanField(default=True)),
+                ('data', models.JSONField(blank=True, default=None, null=True, verbose_name='Podaci tablice dodatnih troškova')),
+                ('total_for_payout', models.DecimalField(decimal_places=2, default=Decimal('0.00'), max_digits=12, verbose_name='Ukupno za isplatu')),
+                ('work_order', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, related_name='additional_costs_table', to='fleet.workorder', verbose_name='Putni nalog')),
+            ],
+            options={
+                'verbose_name': 'Tablica dodatnih troškova putnog naloga',
+                'verbose_name_plural': 'Tablice dodatnih troškova putnog naloga',
+                'ordering': ['-updated_at'],
+            },
+        ),
+    ]

backend/modules/fleet/migrations/0030_merge_20260719_2057.py

@@ -0,0 +1,11 @@
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fleet', '0029_alter_workorder_purpose'),
+        ('fleet', '0029_workorderadditionalcoststable'),
+    ]
+
+    operations = []

backend/modules/fleet/migrations/0031_alter_workorderadditionalcoststable_created_at_and_more.py

@@ -0,0 +1,34 @@
+# Generated by Django 5.2.15 on 2026-07-19 19:01
+
+import uuid
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fleet', '0030_merge_20260719_2057'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='workorderadditionalcoststable',
+            name='created_at',
+            field=models.DateTimeField(auto_now_add=True, verbose_name='Vrijeme kreiranja'),
+        ),
+        migrations.AlterField(
+            model_name='workorderadditionalcoststable',
+            name='id',
+            field=models.UUIDField(default=uuid.uuid4, editable=False, help_text='Unikatni identifikator entiteta (UUID).', primary_key=True, serialize=False),
+        ),
+        migrations.AlterField(
+            model_name='workorderadditionalcoststable',
+            name='is_active',
+            field=models.BooleanField(default=True, verbose_name='Aktivan zapis'),
+        ),
+        migrations.AlterField(
+            model_name='workorderadditionalcoststable',
+            name='updated_at',
+            field=models.DateTimeField(auto_now=True, verbose_name='Vrijeme zadnje izmjene'),
+        ),
+    ]