feat: dodaj bilješke widget i admin kalendar/notifikacije

Uveden je novi Notes drawer s kalendar integracijom, zajednički DRY
left-slide mehanizam te međusobno isključivo prikazivanje s Kalendar
widgetom.

Backend i frontend su prošireni za servisne bilješke (uključujući slanje
na više servisera), dodan je users/servicers endpoint, te su uvedene
warning notifikacije kada serviser ima više od 2 zadatka isti dan.

U admin su dodane stavke za Bilješke i zaseban Kalendar zadataka (proxy
TaskCalendar) radi lakšeg operativnog pregleda.

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

backend/modules/fleet/migrations/0032_servicecontextnote.py

@@ -0,0 +1,41 @@
+# Generated by Django 5.2.15 on 2026-07-20 03:05
+
+import uuid
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('task_management', '0010_alter_tasktemplate_status'),
+        ('fleet', '0031_alter_workorderadditionalcoststable_created_at_and_more'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ServiceContextNote',
+            fields=[
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, help_text='Unikatni identifikator entiteta (UUID).', primary_key=True, serialize=False)),
+                ('created_at', models.DateTimeField(auto_now_add=True, verbose_name='Vrijeme kreiranja')),
+                ('updated_at', models.DateTimeField(auto_now=True, verbose_name='Vrijeme zadnje izmjene')),
+                ('is_active', models.BooleanField(default=True, verbose_name='Aktivan zapis')),
+                ('audience_source', models.CharField(choices=[('self', 'Samo autor'), ('member', 'Odabrani član tima'), ('team', 'Svi članovi tima')], default='self', max_length=16, verbose_name='Publika')),
+                ('note', models.TextField(verbose_name='Bilješka')),
+                ('note_date', models.DateField(blank=True, db_index=True, null=True, verbose_name='Datum podsjetnika')),
+                ('is_closed', models.BooleanField(default=False, verbose_name='Ručno zatvoreno')),
+                ('closed_at', models.DateTimeField(blank=True, null=True, verbose_name='Vrijeme zatvaranja')),
+                ('created_by', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='created_service_context_notes', to=settings.AUTH_USER_MODEL, verbose_name='Kreirao')),
+                ('recipient', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='service_context_notes', to=settings.AUTH_USER_MODEL, verbose_name='Primatelj')),
+                ('task', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='service_context_notes', to='task_management.task', verbose_name='Radni zadatak')),
+                ('work_order', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='service_context_notes', to='fleet.workorder', verbose_name='Putni nalog')),
+            ],
+            options={
+                'verbose_name': 'Bilješka servisnog konteksta',
+                'verbose_name_plural': 'Bilješke servisnog konteksta',
+                'ordering': ['is_closed', 'note_date', '-created_at'],
+            },
+        ),
+    ]