feat: per-task work hours table, notes, and read-only work order data in PDF page

Backend:
- Added service_report_note TextField to Task model (migration 0012)
- Exposed service_report_note in TaskSerializer
- task_service_context: fixed service record filter from
  work_order.vehicle_id -> task.vehicle_id (bug: cross-crane work orders
  returned wrong records for non-primary crane)
- task_service_context: include service_report_note in each task payload
- _build_work_order_service_records_docx_bytes: use per-task
  service_report_note (fallback: work_order.notes); fix service records
  query to use task vehicle ids for cross-crane support
- PDF generator: same per-task notes and cross-crane vehicle fix

Frontend:
- WorkOrderInvoicesPdfPage: removed global 'Uredi tablicu radnih sati' /
  'Uredi tekst napomene' buttons that always opened tasks[0]; replaced
  with per-task buttons inside each task article
- WorkOrderInvoicesPdfPage: separate editingTaskNote state / handler
  that calls updateTaskServiceReportNote (PATCH task.service_report_note)
- WorkOrderServiceNotesModal: now receives task prop instead of workOrder;
  reads/writes task.service_report_note; shows task title in header
- TaskWorkHoursTableModal: added workOrder prop; renders read-only amber
  info block with travel dates, mileage, and servicer vehicle data
- fleetDashboardStore: added updateTaskServiceReportNote() function
- WorkOrderInvoicesPdfPage: show saved service_report_note inline on
  each task card for quick reference

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

backend/modules/task_management/migrations/0012_task_service_report_note.py

@@ -0,0 +1,21 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('task_management', '0011_taskcalendar'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='task',
+            name='service_report_note',
+            field=models.TextField(
+                blank=True,
+                default='',
+                verbose_name='Napomena izvještaja servisera',
+                help_text='Tekst napomene za PDF izvještaj servisera za ovaj zadatak.',
+            ),
+        ),
+    ]