fix: add editable work order travel expenses

Introduce a dedicated travel-expenses table for work orders so Broj sati, Količina dnevnica, and Iznos dnevnice can be reviewed and edited before PDF generation. The PDF now uses the stored travel-expenses values, with default HR rate and cache invalidation on updates.

backend/modules/fleet/migrations/0036_workordertravelexpenses_table.py

@@ -0,0 +1,34 @@
+from decimal import Decimal
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fleet', '0035_generatedfleetarchive'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='WorkOrderTravelExpensesTable',
+            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)),
+                ('broj_sati', models.DecimalField(decimal_places=2, default=Decimal('0.00'), max_digits=10, verbose_name='Broj sati')),
+                ('kolicina_dnevnica', models.DecimalField(decimal_places=2, default=Decimal('0.00'), max_digits=10, verbose_name='Količina dnevnica')),
+                ('iznos_dnevnica', models.DecimalField(decimal_places=2, default=Decimal('30.00'), max_digits=10, verbose_name='Iznos dnevnice')),
+                ('daily_rate_country', models.CharField(choices=[('HR', 'Hrvatska'), ('BIH', 'BiH'), ('SI', 'Slovenija'), ('CG', 'Crna Gora')], default='HR', max_length=8, verbose_name='Država dnevnice')),
+                ('total_for_payout', models.DecimalField(decimal_places=2, default=Decimal('0.00'), max_digits=12, verbose_name='Ukupan iznos')),
+                ('work_order', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, related_name='travel_expenses_table', to='fleet.workorder', verbose_name='Putni nalog')),
+            ],
+            options={
+                'verbose_name': 'Tablica obračuna putnih troškova',
+                'verbose_name_plural': 'Tablice obračuna putnih troškova',
+                'ordering': ['-updated_at'],
+            },
+        ),
+    ]