Phase 1: mobile-first pantry redesign with In/Low/Out state

Track presence (In/Low/Out) as the primary signal instead of exact
quantities; quantity becomes an optional integer, unit optional too
(migration 0003 backfills state from quantity: 0 -> out, else in).

- Pantry rebuilt as a phone-first card list: colored state rail,
  segmented In/Low/Out switch (server-driven HTMX), greyed out-items,
  live summary counts.
- Fast add: bottom add bar with type-ahead autocomplete, location
  picker, and quick-add chips for things you've run out of.
- Per-item menu (move / set expiry / delete); expiry is now an
  optional quiet pill, never required.
- New endpoints: pantry search + set-state; dropped the old
  edit-expiry/cancel flow and its partial.
- Recipes matcher made presence-based (have-it beats have-enough);
  state added to admin. Tests cover state, add/restock, search,
  presence matching, and page rendering.

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

kitchen/migrations/0003_pantryitem_state.py

@@ -0,0 +1,42 @@
+from django.db import migrations, models
+
+
+def backfill_state(apps, schema_editor):
+    """Items at quantity 0 are 'out'; everything else is 'in' (the field default)."""
+    PantryItem = apps.get_model("kitchen", "PantryItem")
+    PantryItem.objects.filter(quantity=0).update(state="out")
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("kitchen", "0002_add_rating_and_preferences"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="pantryitem",
+            name="state",
+            field=models.CharField(
+                choices=[("in", "In stock"), ("low", "Running low"), ("out", "Out")],
+                default="in",
+                max_length=10,
+            ),
+        ),
+        # Runs while quantity is still a Decimal column — 0 matches fine.
+        migrations.RunPython(backfill_state, migrations.RunPython.noop),
+        migrations.AlterField(
+            model_name="pantryitem",
+            name="quantity",
+            field=models.PositiveIntegerField(
+                blank=True,
+                help_text="Optional rough count; In/Low/Out is the primary signal",
+                null=True,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="pantryitem",
+            name="unit",
+            field=models.CharField(blank=True, max_length=20),
+        ),
+    ]