MY SKY: dashboard applet + full-page natal chart — TDD

- User model: sky_birth_dt/lat/lon/place/house_system/chart_data fields (lyric migration 0018)
- Applet seed: my-sky (6×6, dashboard context) via applets migration 0009
- dashboard/sky/ — full monoapplet page: natus form + D3 wheel, LS key scoped to dashboard:sky; saves to User model
- dashboard/sky/preview/ — PySwiss proxy (same logic as epic:natus_preview, no seat check)
- dashboard/sky/save/ — persists 6 sky fields to User via update_fields
- _applet-my-sky.html: tile with h2 link to /dashboard/sky/
- 2 FTs (applet→link→form, localStorage persistence) + 12 ITs — all green

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/apps/applets/migrations/0009_my_sky_applet.py

@@ -0,0 +1,24 @@
+from django.db import migrations
+
+
+def seed_my_sky_applet(apps, schema_editor):
+    Applet = apps.get_model('applets', 'Applet')
+    Applet.objects.get_or_create(
+        slug='my-sky',
+        defaults={
+            'name': 'My Sky',
+            'grid_cols': 6,
+            'grid_rows': 6,
+            'context': 'dashboard',
+        },
+    )
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('applets', '0008_game_kit_applets'),
+    ]
+
+    operations = [
+        migrations.RunPython(seed_my_sky_applet, migrations.RunPython.noop)
+    ]