feat: auto-populate slug fields on save

Add clubmanager.base.unique_slugify(instance, value, scope=...): slugify a
source value, truncate to the field's max_length, and append -2/-3/... to
stay unique within a scope. ClubScopedModel gains a slug_source hook that
fills a blank slug (unique per club) on save.

Wire it up so every SlugField auto-populates from its natural source when
left blank (explicit values are always kept):
- shop.Product.slug   <- name   (per club)
- formbuilder.Form.slug <- title (per club)
- formbuilder.Field.key <- label (per form)
Club.slug already auto-populated; refactor it onto the shared helper.

Also fix shop.Product.slug's multi-tenancy bug: it was globally unique
(unique=True); make it unique per club like the others. Migrations added.
Full suite at 100% coverage.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

shop/migrations/0001_initial.py

@@ -0,0 +1,29 @@
+# Generated by Django 6.0.6 on 2026-07-12 19:29
+
+import django.db.models.deletion
+import uuid
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('club', '0008_alter_clubmembership_unique_together_and_more'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Product',
+            fields=[
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('name', models.CharField(max_length=255, verbose_name='name')),
+                ('slug', models.SlugField(max_length=255, unique=True, verbose_name='slug')),
+                ('club', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='%(class)ss', to='club.club')),
+            ],
+            options={
+                'abstract': False,
+            },
+        ),
+    ]

shop/migrations/0002_alter_product_slug_and_more.py

@@ -0,0 +1,23 @@
+# Generated by Django 6.0.6 on 2026-07-12 19:39
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('club', '0008_alter_clubmembership_unique_together_and_more'),
+        ('shop', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='product',
+            name='slug',
+            field=models.SlugField(blank=True, max_length=255, verbose_name='slug'),
+        ),
+        migrations.AddConstraint(
+            model_name='product',
+            constraint=models.UniqueConstraint(fields=('club', 'slug'), name='unique_product_slug_per_club'),
+        ),
+    ]

shop/models.py

@@ -1 +1,17 @@
-# Create your models here.
+from django.db import models
+from django.db.models import UniqueConstraint
+from django.utils.translation import gettext_lazy as _
+
+from clubmanager.base import ClubScopedModel
+
+
+class Product(ClubScopedModel):
+    name = models.CharField(_("name"), max_length=255)
+    slug = models.SlugField(_("slug"), max_length=255, blank=True)
+
+    slug_source = "name"
+
+    class Meta:
+        constraints = [
+            UniqueConstraint(fields=["club", "slug"], name="unique_product_slug_per_club"),
+        ]

shop/tests.py

@@ -1 +1,39 @@
-# Create your tests here.
+from django.test import TestCase
+
+from club.models import Club
+
+from .models import Product
+
+
+class ProductSlugTests(TestCase):
+    def setUp(self):
+        self.club = Club.objects.create(name="Ajax United", slug="ajax-united")
+
+    def test_slug_auto_populated_from_name(self):
+        product = Product.objects.create(club=self.club, name="Home Jersey")
+
+        self.assertEqual(product.slug, "home-jersey")
+
+    def test_explicit_slug_is_preserved(self):
+        product = Product.objects.create(club=self.club, name="Home Jersey", slug="custom")
+
+        self.assertEqual(product.slug, "custom")
+
+    def test_slug_is_unique_per_club_with_suffix(self):
+        first = Product.objects.create(club=self.club, name="Home Jersey")
+        second = Product.objects.create(club=self.club, name="Home Jersey")
+
+        self.assertEqual(first.slug, "home-jersey")
+        self.assertEqual(second.slug, "home-jersey-2")
+
+    def test_same_slug_allowed_in_a_different_club(self):
+        other = Club.objects.create(name="Rival FC", slug="rival-fc")
+        here = Product.objects.create(club=self.club, name="Home Jersey")
+        there = Product.objects.create(club=other, name="Home Jersey")
+
+        self.assertEqual(here.slug, there.slug)
+
+    def test_unsluggable_name_falls_back(self):
+        product = Product.objects.create(club=self.club, name="###")
+
+        self.assertEqual(product.slug, "item")