fix: remove broken dev_tools router references after API route migration

The dev_tools API routes were moved to the monitoring module, but several
files still tried to import the non-existent admin_router. This caused
warnings during app startup.

Changes:
- Remove _get_admin_router() from definition.py
- Clear routes/__init__.py and routes/api/__init__.py of broken imports
- Update exceptions.py to import from monitoring.exceptions
- Update code_quality_service.py to import from monitoring.exceptions

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

app/modules/dev_tools/routes/api/__init__.py

@@ -2,13 +2,9 @@
 """
 Dev-Tools module API routes.
 
-Provides REST API endpoints for code quality and test running:
-- Admin API: Code quality scans, violations, test execution
-
-Note: Dev-tools is an internal module, so there are no vendor routes.
-Currently re-exports routes from the legacy location.
+Note: Code quality and test running routes have been moved to the monitoring module.
+The dev_tools module keeps models but routes are now in monitoring.
 """
 
-from app.modules.dev_tools.routes.api.admin import admin_router
-
-__all__ = ["admin_router"]
+# No routes exported - code quality and tests are in monitoring module
+__all__ = []