feat: add customer multiple addresses management

- Add CustomerAddressService with CRUD operations
- Add shop API endpoints for address management (GET, POST, PUT, DELETE)
- Add set default endpoint for address type
- Implement addresses.html with full UI (cards, modals, Alpine.js)
- Integrate saved addresses in checkout flow
  - Address selector dropdowns for shipping/billing
  - Auto-select default addresses
  - Save new address checkbox option
- Add country_iso field alongside country_name
- Add address exceptions (NotFound, LimitExceeded, InvalidType)
- Max 10 addresses per customer limit
- One default address per type (shipping/billing)
- Add unit tests for CustomerAddressService
- Add integration tests for shop addresses API

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/fixtures/customer_fixtures.py

@@ -32,7 +32,7 @@ def test_customer(db, test_vendor):
 
 @pytest.fixture
 def test_customer_address(db, test_vendor, test_customer):
-    """Create a test customer address."""
+    """Create a test customer shipping address."""
     address = CustomerAddress(
         vendor_id=test_vendor.id,
         customer_id=test_customer.id,
@@ -42,7 +42,8 @@ def test_customer_address(db, test_vendor, test_customer):
         address_line_1="123 Main St",
         city="Luxembourg",
         postal_code="L-1234",
-        country="Luxembourg",
+        country_name="Luxembourg",
+        country_iso="LU",
         is_default=True,
     )
     db.add(address)
@@ -51,6 +52,55 @@ def test_customer_address(db, test_vendor, test_customer):
     return address
 
 
+@pytest.fixture
+def test_customer_billing_address(db, test_vendor, test_customer):
+    """Create a test customer billing address."""
+    address = CustomerAddress(
+        vendor_id=test_vendor.id,
+        customer_id=test_customer.id,
+        address_type="billing",
+        first_name="John",
+        last_name="Doe",
+        company="Test Company S.A.",
+        address_line_1="456 Business Ave",
+        city="Luxembourg",
+        postal_code="L-5678",
+        country_name="Luxembourg",
+        country_iso="LU",
+        is_default=True,
+    )
+    db.add(address)
+    db.commit()
+    db.refresh(address)
+    return address
+
+
+@pytest.fixture
+def test_customer_multiple_addresses(db, test_vendor, test_customer):
+    """Create multiple addresses for testing limits and listing."""
+    addresses = []
+    for i in range(3):
+        address = CustomerAddress(
+            vendor_id=test_vendor.id,
+            customer_id=test_customer.id,
+            address_type="shipping" if i % 2 == 0 else "billing",
+            first_name=f"Name{i}",
+            last_name="Test",
+            address_line_1=f"{i}00 Test Street",
+            city="Luxembourg",
+            postal_code=f"L-{1000+i}",
+            country_name="Luxembourg",
+            country_iso="LU",
+            is_default=(i == 0),
+        )
+        db.add(address)
+        addresses.append(address)
+    db.commit()
+    for addr in addresses:
+        db.refresh(addr)
+    return addresses
+
+
 @pytest.fixture
 def test_order(db, test_vendor, test_customer, test_customer_address):
     """Create a test order with customer/address snapshots."""