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/routers/tasks.py

@@ -9,7 +9,7 @@ from datetime import datetime
 
 from database import get_db
 from models.task import Task, ProductionNote, TaskAttachment, Submission, Review, NoteType
-from models.user import User, UserRole, DepartmentRole
+from models.user import User, UserRole
 from models.project import Project, ProjectMember
 from models.asset import Asset
 from models.shot import Shot
@@ -248,6 +248,7 @@ async def get_tasks(
                 "name": task.name,
                 "task_type": task.task_type,
                 "status": task.status,
+                "department": task.department,
                 "start_date": task.start_date,
                 "deadline": task.deadline,
                 "project_id": task.project_id,
@@ -330,6 +331,7 @@ async def get_my_tasks(
                 name=task.name,
                 task_type=task.task_type,
                 status=task.status,
+                department=task.department,
                 start_date=task.start_date,
                 deadline=task.deadline,
                 project_id=task.project_id,
@@ -740,6 +742,7 @@ async def get_task(
         "description": task.description,
         "task_type": task.task_type,
         "status": task.status,
+        "department": task.department,
         "start_date": task.start_date,
         "deadline": task.deadline,
         "project_id": task.project_id,
@@ -866,6 +869,7 @@ async def update_task(
         "description": task.description,
         "task_type": task.task_type,
         "status": task.status,
+        "department": task.department,
         "start_date": task.start_date,
         "deadline": task.deadline,
         "project_id": task.project_id,
@@ -958,6 +962,7 @@ async def update_task_status(
         "description": task.description,
         "task_type": task.task_type,
         "status": task.status,
+        "department": task.department,
         "start_date": task.start_date,
         "deadline": task.deadline,
         "project_id": task.project_id,
@@ -1024,13 +1029,13 @@ async def assign_task(
     
     # Check if user's department role matches task type (optional validation)
     task_to_department_mapping = {
-        "layout": DepartmentRole.LAYOUT,
-        "animation": DepartmentRole.ANIMATION,
-        "lighting": DepartmentRole.LIGHTING,
-        "compositing": DepartmentRole.COMPOSITE,
-        "modeling": DepartmentRole.MODELING,
-        "rigging": DepartmentRole.RIGGING,
-        "surfacing": DepartmentRole.SURFACING,
+        "layout": "layout",
+        "animation": "animation",
+        "lighting": "lighting",
+        "compositing": "composite",
+        "modeling": "modeling",
+        "rigging": "rigging",
+        "surfacing": "surfacing",
         "simulation": None  # Simulation can be handled by multiple departments
     }
     
@@ -1064,6 +1069,7 @@ async def assign_task(
         "description": task.description,
         "task_type": task.task_type,
         "status": task.status,
+        "department": task.department,
         "start_date": task.start_date,
         "deadline": task.deadline,
         "project_id": task.project_id,