fix: replace non-existent BadRequestException with ValidationException

BadRequestException doesn't exist in app.exceptions. Use
ValidationException for module code validation errors.

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

app/api/v1/admin/module_config.py

@@ -18,6 +18,7 @@ from pydantic import BaseModel, Field
 from sqlalchemy.orm import Session
 
 from app.api.deps import get_current_super_admin, get_db
+from app.exceptions import ValidationException
 from app.modules.registry import MODULES
 from app.modules.service import module_service
 from app.services.platform_service import platform_service
@@ -274,14 +275,12 @@ async def get_module_config(
     Returns current config values merged with defaults.
     Super admin only.
     """
-    from app.exceptions import BadRequestException
-
     # Verify platform exists
     platform = platform_service.get_platform_by_id(db, platform_id)
 
     # Validate module code
     if module_code not in MODULES:
-        raise BadRequestException(f"Unknown module: {module_code}")
+        raise ValidationException(f"Unknown module: {module_code}")
 
     module = MODULES[module_code]
 
@@ -319,14 +318,12 @@ async def update_module_config(
 
     Super admin only.
     """
-    from app.exceptions import BadRequestException
-
     # Verify platform exists
     platform = platform_service.get_platform_by_id(db, platform_id)
 
     # Validate module code
     if module_code not in MODULES:
-        raise BadRequestException(f"Unknown module: {module_code}")
+        raise ValidationException(f"Unknown module: {module_code}")
 
     module = MODULES[module_code]
 
@@ -365,11 +362,9 @@ async def get_config_defaults(
     Returns the default config values and schema for a module.
     Super admin only.
     """
-    from app.exceptions import BadRequestException
-
     # Validate module code
     if module_code not in MODULES:
-        raise BadRequestException(f"Unknown module: {module_code}")
+        raise ValidationException(f"Unknown module: {module_code}")
 
     module = MODULES[module_code]
 
@@ -398,14 +393,12 @@ async def reset_module_config(
 
     Super admin only.
     """
-    from app.exceptions import BadRequestException
-
     # Verify platform exists
     platform = platform_service.get_platform_by_id(db, platform_id)
 
     # Validate module code
     if module_code not in MODULES:
-        raise BadRequestException(f"Unknown module: {module_code}")
+        raise ValidationException(f"Unknown module: {module_code}")
 
     # Reset to defaults
     defaults = MODULE_CONFIG_DEFAULTS.get(module_code, {})