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>

app/modules/inventory/exceptions.py

@@ -2,17 +2,18 @@
 """
 Inventory module exceptions.
 
-Re-exports inventory-related exceptions from their source locations.
+This module provides exception classes for inventory operations including:
+- Inventory record management
+- Quantity validation
+- Location management
 """
 
-from app.exceptions.inventory import (
-    InventoryNotFoundException,
-    InsufficientInventoryException,
-    InvalidInventoryOperationException,
-    InventoryValidationException,
-    NegativeInventoryException,
-    InvalidQuantityException,
-    LocationNotFoundException,
+from typing import Any
+
+from app.exceptions.base import (
+    BusinessLogicException,
+    ResourceNotFoundException,
+    ValidationException,
 )
 
 __all__ = [
@@ -24,3 +25,130 @@ __all__ = [
     "InvalidQuantityException",
     "LocationNotFoundException",
 ]
+
+
+class InventoryNotFoundException(ResourceNotFoundException):
+    """Raised when inventory record is not found."""
+
+    def __init__(self, identifier: str, identifier_type: str = "ID"):
+        if identifier_type.lower() == "gtin":
+            message = f"No inventory found for GTIN '{identifier}'"
+        else:
+            message = (
+                f"Inventory record with {identifier_type} '{identifier}' not found"
+            )
+
+        super().__init__(
+            resource_type="Inventory",
+            identifier=identifier,
+            message=message,
+            error_code="INVENTORY_NOT_FOUND",
+        )
+
+
+class InsufficientInventoryException(BusinessLogicException):
+    """Raised when trying to remove more inventory than available."""
+
+    def __init__(
+        self,
+        gtin: str,
+        location: str,
+        requested: int,
+        available: int,
+    ):
+        message = f"Insufficient inventory for GTIN '{gtin}' at '{location}'. Requested: {requested}, Available: {available}"
+
+        super().__init__(
+            message=message,
+            error_code="INSUFFICIENT_INVENTORY",
+            details={
+                "gtin": gtin,
+                "location": location,
+                "requested_quantity": requested,
+                "available_quantity": available,
+            },
+        )
+
+
+class InvalidInventoryOperationException(ValidationException):
+    """Raised when inventory operation is invalid."""
+
+    def __init__(
+        self,
+        message: str,
+        operation: str | None = None,
+        details: dict[str, Any] | None = None,
+    ):
+        if not details:
+            details = {}
+
+        if operation:
+            details["operation"] = operation
+
+        super().__init__(
+            message=message,
+            details=details,
+        )
+        self.error_code = "INVALID_INVENTORY_OPERATION"
+
+
+class InventoryValidationException(ValidationException):
+    """Raised when inventory data validation fails."""
+
+    def __init__(
+        self,
+        message: str = "Inventory validation failed",
+        field: str | None = None,
+        validation_errors: dict[str, str] | None = None,
+    ):
+        details = {}
+        if validation_errors:
+            details["validation_errors"] = validation_errors
+
+        super().__init__(
+            message=message,
+            field=field,
+            details=details,
+        )
+        self.error_code = "INVENTORY_VALIDATION_FAILED"
+
+
+class NegativeInventoryException(BusinessLogicException):
+    """Raised when inventory quantity would become negative."""
+
+    def __init__(self, gtin: str, location: str, resulting_quantity: int):
+        message = f"Inventory operation would result in negative quantity ({resulting_quantity}) for GTIN '{gtin}' at '{location}'"
+
+        super().__init__(
+            message=message,
+            error_code="NEGATIVE_INVENTORY_NOT_ALLOWED",
+            details={
+                "gtin": gtin,
+                "location": location,
+                "resulting_quantity": resulting_quantity,
+            },
+        )
+
+
+class InvalidQuantityException(ValidationException):
+    """Raised when quantity value is invalid."""
+
+    def __init__(self, quantity: Any, message: str = "Invalid quantity"):
+        super().__init__(
+            message=f"{message}: {quantity}",
+            field="quantity",
+            details={"quantity": quantity},
+        )
+        self.error_code = "INVALID_QUANTITY"
+
+
+class LocationNotFoundException(ResourceNotFoundException):
+    """Raised when inventory location is not found."""
+
+    def __init__(self, location: str):
+        super().__init__(
+            resource_type="Location",
+            identifier=location,
+            message=f"Inventory location '{location}' not found",
+            error_code="LOCATION_NOT_FOUND",
+        )