Add per-project Department management

Departments are now a customizable per-project list (standard + custom),
matching the existing custom task type/status pattern, instead of a fixed
7-value enum. They're usable directly on tasks (new field, independent of
assignee) and continue to drive team member department roles.

backend/models/user.py

@@ -12,16 +12,6 @@ class UserRole(str, enum.Enum):
     DEVELOPER = "developer"
 
 
-class DepartmentRole(str, enum.Enum):
-    LAYOUT = "layout"
-    ANIMATION = "animation"
-    LIGHTING = "lighting"
-    COMPOSITE = "composite"
-    MODELING = "modeling"
-    RIGGING = "rigging"
-    SURFACING = "surfacing"
-
-
 class User(Base):
     __tablename__ = "users"