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/exceptions.py

@@ -12,9 +12,8 @@ from app.exceptions.base import (
     ResourceNotFoundException,
 )
 
-# Re-export code quality exceptions from legacy location
-# This avoids circular imports since app/exceptions/__init__.py imports code_quality.py
-from app.exceptions.code_quality import (
+# Re-export code quality exceptions from their module location
+from app.modules.monitoring.exceptions import (
     ViolationNotFoundException,
     ScanNotFoundException,
     ScanExecutionException,