feat(ad_control): new AdSurface + AdPlacement module for placement-based featured/top events

- New ad_control Django app: AdSurface + AdPlacement models with GLOBAL/LOCAL scope
- Admin CRUD API at /api/v1/ad-control/ (JWT-protected): surfaces, placements, picker events
- Placement lifecycle: DRAFT → ACTIVE|SCHEDULED → EXPIRED|DISABLED
- LOCAL scope: Haversine ≤ 50km from event lat/lng (fixed radius, no config needed)
- Consumer APIs: /api/events/featured-events/ and /api/events/top-events/ rewritten
  to use placement-based queries (same URL paths + response shape — no breaking changes)
- Seed command: seed_surfaces --migrate converts existing is_featured/is_top_event booleans
- mount: admin_api/urls.py → ad-control/, mobile_api/urls.py → replaced consumer views
- settings.py: added ad_control to INSTALLED_APPS

ad_control/migrations/0001_initial.py

@@ -0,0 +1,104 @@
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('events', '0007_add_is_featured_is_top_event'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='AdSurface',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('key', models.CharField(db_index=True, max_length=50, unique=True)),
+                ('name', models.CharField(max_length=100)),
+                ('description', models.TextField(blank=True, default='')),
+                ('max_slots', models.IntegerField(default=8)),
+                ('layout_type', models.CharField(
+                    choices=[('carousel', 'Carousel'), ('grid', 'Grid'), ('list', 'List')],
+                    default='carousel', max_length=20,
+                )),
+                ('sort_behavior', models.CharField(
+                    choices=[('rank', 'By Rank'), ('date', 'By Date'), ('popularity', 'By Popularity')],
+                    default='rank', max_length=20,
+                )),
+                ('is_active', models.BooleanField(default=True)),
+                ('created_at', models.DateTimeField(auto_now_add=True)),
+            ],
+            options={
+                'verbose_name': 'Ad Surface',
+                'verbose_name_plural': 'Ad Surfaces',
+                'ordering': ['name'],
+            },
+        ),
+        migrations.CreateModel(
+            name='AdPlacement',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('status', models.CharField(
+                    choices=[
+                        ('DRAFT', 'Draft'), ('ACTIVE', 'Active'), ('SCHEDULED', 'Scheduled'),
+                        ('EXPIRED', 'Expired'), ('DISABLED', 'Disabled'),
+                    ],
+                    db_index=True, default='DRAFT', max_length=20,
+                )),
+                ('priority', models.CharField(
+                    choices=[('SPONSORED', 'Sponsored'), ('MANUAL', 'Manual'), ('ALGO', 'Algorithm')],
+                    default='MANUAL', max_length=20,
+                )),
+                ('scope', models.CharField(
+                    choices=[
+                        ('GLOBAL', 'Global \u2014 shown to all users'),
+                        ('LOCAL', 'Local \u2014 shown to nearby users (50 km radius)'),
+                    ],
+                    db_index=True, default='GLOBAL', max_length=10,
+                )),
+                ('rank', models.IntegerField(default=0, help_text='Lower rank = higher position')),
+                ('start_at', models.DateTimeField(blank=True, help_text='When this placement becomes active', null=True)),
+                ('end_at', models.DateTimeField(blank=True, help_text='When this placement expires', null=True)),
+                ('boost_label', models.CharField(
+                    blank=True, default='', help_text='Display label e.g. "Featured", "Top Pick", "Sponsored"',
+                    max_length=50,
+                )),
+                ('notes', models.TextField(blank=True, default='')),
+                ('created_at', models.DateTimeField(auto_now_add=True)),
+                ('updated_at', models.DateTimeField(auto_now=True)),
+                ('created_by', models.ForeignKey(
+                    blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL,
+                    related_name='created_placements', to=settings.AUTH_USER_MODEL,
+                )),
+                ('event', models.ForeignKey(
+                    on_delete=django.db.models.deletion.CASCADE, related_name='ad_placements',
+                    to='events.event',
+                )),
+                ('surface', models.ForeignKey(
+                    on_delete=django.db.models.deletion.CASCADE, related_name='placements',
+                    to='ad_control.adsurface',
+                )),
+                ('updated_by', models.ForeignKey(
+                    blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL,
+                    related_name='updated_placements', to=settings.AUTH_USER_MODEL,
+                )),
+            ],
+            options={
+                'verbose_name': 'Ad Placement',
+                'verbose_name_plural': 'Ad Placements',
+                'ordering': ['rank', '-created_at'],
+            },
+        ),
+        migrations.AddConstraint(
+            model_name='adplacement',
+            constraint=models.UniqueConstraint(
+                condition=models.Q(('status__in', ['DRAFT', 'ACTIVE', 'SCHEDULED'])),
+                fields=('surface', 'event'),
+                name='unique_active_placement_per_surface',
+            ),
+        ),
+    ]