refactor: remove all backward compatibility code across 70 files

Clean up 28 backward compatibility instances identified in the codebase.
The app is not live, so all shims are replaced with the target architecture:

- Remove legacy Inventory.location column (use bin_location exclusively)
- Remove dashboard _extract_metric_value helper (use flat metrics dict)
- Remove legacy stat field duplicates (total_stores, total_imports, etc.)
- Remove 13 re-export shims and class aliases across modules
- Remove module-enabling JSON fallback (use PlatformModule junction table)
- Remove menu_to_legacy_format() conversion (return dataclasses directly)
- Remove title/description from MarketplaceProductBase schema
- Clean billing convenience method docstrings
- Clean test fixtures and backward-compat comments
- Add PlatformModule seeding to init_production.py

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

tests/unit/middleware/test_platform_context.py

@@ -13,7 +13,7 @@ Tests cover:
 URL Structure:
 - Main marketing site: localhost:9999/ (no prefix) -> 'main' platform
 - Platform sites: localhost:9999/platforms/{code}/ -> specific platform
-- Production: domain-based (oms.lu, loyalty.lu)
+- Production: domain-based (omsflow.lu, rewardflow.lu)
 """
 
 from unittest.mock import AsyncMock, MagicMock, Mock, patch
@@ -42,35 +42,35 @@ class TestPlatformContextManager:
     # ========================================================================
 
     def test_detect_domain_based_platform(self):
-        """Test domain-based platform detection for production (e.g., oms.lu)."""
+        """Test domain-based platform detection for production (e.g., omsflow.lu)."""
         request = Mock(spec=Request)
-        request.headers = {"host": "oms.lu"}
+        request.headers = {"host": "omsflow.lu"}
         request.url = Mock(path="/pricing")
 
         context = PlatformContextManager.detect_platform_context(request)
 
         assert context is not None
         assert context["detection_method"] == "domain"
-        assert context["domain"] == "oms.lu"
-        assert context["host"] == "oms.lu"
+        assert context["domain"] == "omsflow.lu"
+        assert context["host"] == "omsflow.lu"
         assert context["original_path"] == "/pricing"
 
     def test_detect_domain_with_port(self):
         """Test domain detection with port number."""
         request = Mock(spec=Request)
-        request.headers = {"host": "loyalty.lu:8443"}
+        request.headers = {"host": "rewardflow.lu:8443"}
         request.url = Mock(path="/features")
 
         context = PlatformContextManager.detect_platform_context(request)
 
         assert context is not None
         assert context["detection_method"] == "domain"
-        assert context["domain"] == "loyalty.lu"
+        assert context["domain"] == "rewardflow.lu"
 
     def test_detect_domain_three_level_not_detected(self):
         """Test that three-level domains (subdomains) are not detected as platform domains."""
         request = Mock(spec=Request)
-        request.headers = {"host": "store.oms.lu"}
+        request.headers = {"host": "store.omsflow.lu"}
         request.url = Mock(path="/shop")
 
         context = PlatformContextManager.detect_platform_context(request)
@@ -295,7 +295,7 @@ class TestPlatformContextManager:
 
         mock_db.query.return_value.filter.return_value.filter.return_value.first.return_value = mock_platform
 
-        context = {"detection_method": "domain", "domain": "oms.lu"}
+        context = {"detection_method": "domain", "domain": "omsflow.lu"}
 
         platform = PlatformContextManager.get_platform_from_context(mock_db, context)
 
@@ -398,7 +398,7 @@ class TestPlatformContextManager:
         request = Mock(spec=Request)
         request.url = Mock(path="/pricing")
 
-        context = {"detection_method": "domain", "domain": "oms.lu"}
+        context = {"detection_method": "domain", "domain": "omsflow.lu"}
 
         clean_path = PlatformContextManager.extract_clean_path(request, context)
 
@@ -598,7 +598,7 @@ class TestPlatformContextMiddleware:
         scope = {
             "type": "http",
             "path": "/pricing",
-            "headers": [(b"host", b"oms.lu")],
+            "headers": [(b"host", b"omsflow.lu")],
         }
 
         receive = AsyncMock()
@@ -918,7 +918,7 @@ class TestEdgeCases:
 
     def test_admin_subdomain_with_production_domain(self):
         """Test admin subdomain detection for production domains."""
-        assert FrontendDetector.is_admin("admin.oms.lu", "/dashboard") is True
+        assert FrontendDetector.is_admin("admin.omsflow.lu", "/dashboard") is True
 
     def test_static_file_case_insensitive(self):
         """Test static file detection is case-insensitive."""
@@ -945,7 +945,7 @@ class TestURLRoutingSummary:
     - Main marketing: localhost:9999/ -> 'main' platform, path unchanged
     - OMS platform: localhost:9999/platforms/oms/pricing -> 'oms' platform, path=/pricing
     - Loyalty platform: localhost:9999/platforms/loyalty/features -> 'loyalty' platform, path=/features
-    - Production OMS: oms.lu/pricing -> 'oms' platform, path=/pricing (no rewrite)
+    - Production OMS: omsflow.lu/pricing -> 'oms' platform, path=/pricing (no rewrite)
     """
 
     def test_main_marketing_site_routing(self):
@@ -987,11 +987,11 @@ class TestURLRoutingSummary:
     def test_production_domain_routing(self):
         """Document: Production domains don't rewrite path."""
         request = Mock(spec=Request)
-        request.headers = {"host": "oms.lu"}
+        request.headers = {"host": "omsflow.lu"}
         request.url = Mock(path="/pricing")
 
         context = PlatformContextManager.detect_platform_context(request)
 
         assert context["detection_method"] == "domain"
-        assert context["domain"] == "oms.lu"
+        assert context["domain"] == "omsflow.lu"
         # clean_path not set for domain detection - uses original path