feat(pricing): add workspace user rates and price units

apps/projects/services/rates.py

@@ -1,42 +0,0 @@
-from apps.projects.models import ProjectRate, ProjectUserRate
-
-def create_project_rate(project, hourly_rate, currency="USD"):
-    return ProjectRate.objects.create(
-        project=project,
-        hourly_rate=hourly_rate,
-        currency=currency
-    )
-
-def update_project_rate(rate_instance, **kwargs):
-    update_fields = []
-    for field, value in kwargs.items():
-        if hasattr(rate_instance, field) and getattr(rate_instance, field) != value:
-            setattr(rate_instance, field, value)
-            update_fields.append(field)
-            
-    if update_fields:
-        update_fields.append("updated_at")
-        rate_instance.save(update_fields=update_fields)
-        
-    return rate_instance
-
-def create_project_user_rate(project, user_id, hourly_rate, currency="USD"):
-    return ProjectUserRate.objects.create(
-        project=project,
-        user_id=user_id,
-        hourly_rate=hourly_rate,
-        currency=currency
-    )
-
-def update_project_user_rate(user_rate_instance, **kwargs):
-    update_fields = []
-    for field, value in kwargs.items():
-        if hasattr(user_rate_instance, field) and getattr(user_rate_instance, field) != value:
-            setattr(user_rate_instance, field, value)
-            update_fields.append(field)
-            
-    if update_fields:
-        update_fields.append("updated_at")
-        user_rate_instance.save(update_fields=update_fields)
-        
-    return user_rate_instance