refactor: migrate templates and static files to self-contained modules

Templates Migration:
- Migrate admin templates to modules (tenancy, billing, monitoring, marketplace, etc.)
- Migrate vendor templates to modules (tenancy, billing, orders, messaging, etc.)
- Migrate storefront templates to modules (catalog, customers, orders, cart, checkout, cms)
- Migrate public templates to modules (billing, marketplace, cms)
- Keep shared templates in app/templates/ (base.html, errors/, partials/, macros/)
- Migrate letzshop partials to marketplace module

Static Files Migration:
- Migrate admin JS to modules: tenancy (23 files), core (5 files), monitoring (1 file)
- Migrate vendor JS to modules: tenancy (4 files), core (2 files)
- Migrate shared JS: vendor-selector.js to core, media-picker.js to cms
- Migrate storefront JS: storefront-layout.js to core
- Keep framework JS in static/ (api-client, utils, money, icons, log-config, lib/)
- Update all template references to use module_static paths

Naming Consistency:
- Rename static/platform/ to static/public/
- Rename app/templates/platform/ to app/templates/public/
- Update all extends and static references

Documentation:
- Update module-system.md with shared templates documentation
- Update frontend-structure.md with new module JS organization

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

tests/unit/services/test_inventory_service.py

@@ -5,14 +5,14 @@ import uuid
 
 import pytest
 
-from app.exceptions import (
+from app.modules.inventory.exceptions import (
     InsufficientInventoryException,
     InvalidQuantityException,
     InventoryNotFoundException,
     InventoryValidationException,
-    ProductNotFoundException,
 )
-from app.services.inventory_service import InventoryService
+from app.modules.catalog.exceptions import ProductNotFoundException
+from app.modules.inventory.services.inventory_service import InventoryService
 from app.modules.inventory.models import Inventory
 from app.modules.inventory.schemas import (
     InventoryAdjust,
@@ -126,7 +126,7 @@ class TestInventoryService:
 
     def test_set_inventory_product_not_found(self, db, test_vendor):
         """Test setting inventory for non-existent product raises exception."""
-        from app.exceptions.base import ValidationException
+        from app.exceptions import ValidationException
 
         unique_id = str(uuid.uuid4())[:8].upper()
         inventory_data = InventoryCreate(
@@ -203,7 +203,7 @@ class TestInventoryService:
         self, db, test_inventory, test_product, test_vendor
     ):
         """Test removing more than available raises exception."""
-        from app.exceptions.base import ValidationException
+        from app.exceptions import ValidationException
 
         inventory_data = InventoryAdjust(
             product_id=test_product.id,
@@ -251,7 +251,7 @@ class TestInventoryService:
         self, db, test_inventory, test_product, test_vendor
     ):
         """Test reserving more than available raises exception."""
-        from app.exceptions.base import ValidationException
+        from app.exceptions import ValidationException
 
         available = test_inventory.quantity - test_inventory.reserved_quantity
 
@@ -335,7 +335,7 @@ class TestInventoryService:
         self, db, test_inventory, test_product, test_vendor
     ):
         """Test fulfilling more than quantity raises exception."""
-        from app.exceptions.base import ValidationException
+        from app.exceptions import ValidationException
 
         reserve_data = InventoryReserve(
             product_id=test_product.id,
@@ -401,7 +401,7 @@ class TestInventoryService:
 
     def test_get_product_inventory_not_found(self, db, test_vendor):
         """Test getting inventory for non-existent product raises exception."""
-        from app.exceptions.base import ValidationException
+        from app.exceptions import ValidationException
 
         # Service wraps ProductNotFoundException in ValidationException
         with pytest.raises((ProductNotFoundException, ValidationException)):
@@ -675,7 +675,7 @@ class TestInventoryService:
 
     def test_get_vendor_inventory_admin_vendor_not_found(self, db):
         """Test get_vendor_inventory_admin raises for non-existent vendor."""
-        from app.exceptions import VendorNotFoundException
+        from app.modules.tenancy.exceptions import VendorNotFoundException
 
         with pytest.raises(VendorNotFoundException):
             self.service.get_vendor_inventory_admin(db, vendor_id=99999)
@@ -700,7 +700,7 @@ class TestInventoryService:
 
     def test_verify_vendor_exists_not_found(self, db):
         """Test verify_vendor_exists raises for non-existent vendor."""
-        from app.exceptions import VendorNotFoundException
+        from app.modules.tenancy.exceptions import VendorNotFoundException
 
         with pytest.raises(VendorNotFoundException):
             self.service.verify_vendor_exists(db, 99999)