feat(projects): add projects app's basic structure and endpoints

apps/projects/services/projects.py

@@ -0,0 +1,74 @@
+from django.db import transaction
+from rest_framework.exceptions import ValidationError, PermissionDenied
+
+from apps.projects.models import Project, ProjectMembership
+from apps.workspaces.models import WorkspaceMembership
+
+
+@transaction.atomic
+def create_project(user, workspace, name, client=None, description="", color=""):
+    """
+    Creates a new project and automatically assigns the creator 
+    as an active MANAGER of that project.
+    """
+    workspace_member = WorkspaceMembership.objects.filter(
+        workspace=workspace,
+        user=user,
+        is_active=True,
+        is_deleted=False
+    ).first()
+    
+    if not workspace_member:
+        raise PermissionDenied("You do not have access to this workspace.")
+
+    if Project.objects.filter(workspace=workspace, name=name, is_deleted=False).exists():
+        raise ValidationError({"name": "A project with this name already exists in the workspace."})
+
+    project = Project.objects.create(
+        workspace=workspace,
+        name=name,
+        client=client,
+        description=description,
+        color=color
+    )
+
+    ProjectMembership.objects.create(
+        project=project,
+        user=user,
+        role=ProjectMembership.Role.MANAGER,
+        is_active=True
+    )
+
+    return project
+
+
+def update_project(project, **kwargs):
+    """
+    Updates specific fields of an existing project.
+    """
+    update_fields = []
+    
+    # Optional manual uniqueness check if name is being updated
+    if "name" in kwargs and kwargs["name"] != project.name:
+        if Project.objects.filter(workspace=project.workspace, name=kwargs["name"], is_deleted=False).exists():
+            raise ValidationError({"name": "A project with this name already exists in the workspace."})
+
+    for field, value in kwargs.items():
+        if hasattr(project, field) and getattr(project, field) != value:
+            setattr(project, field, value)
+            update_fields.append(field)
+            
+    if update_fields:
+        update_fields.append("updated_at")
+        project.save(update_fields=update_fields)
+        
+    return project
+
+
+def toggle_project_archive(project) -> Project:
+    """
+    Archives or unarchives a project.
+    """
+    project.is_archived = not project.is_archived
+    project.save(update_fields=["is_archived", "updated_at"])
+    return project