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.

frontend/src/components/task/TaskDetailPanel.vue

@@ -123,7 +123,22 @@
                     <Badge variant="outline">{{ formatTaskType(task.task_type) }}</Badge>
                   </p>
                 </div>
-                <div></div>
+                <div>
+                  <Label class="text-muted-foreground">Department</Label>
+                  <div class="mt-1">
+                    <Select :model-value="localDepartment || 'none'" @update:model-value="(value) => handleDepartmentChange(value === 'none' ? '' : (value as string))">
+                      <SelectTrigger class="h-8">
+                        <SelectValue placeholder="None" />
+                      </SelectTrigger>
+                      <SelectContent>
+                        <SelectItem value="none">None</SelectItem>
+                        <SelectItem v-for="department in departmentOptions" :key="department" :value="department">
+                          {{ formatDepartment(department) }}
+                        </SelectItem>
+                      </SelectContent>
+                    </Select>
+                  </div>
+                </div>
                 <div>
                   <Label class="text-muted-foreground">Start Date</Label>
                   <div class="mt-1">
@@ -341,6 +356,7 @@ import TaskAttachments from './TaskAttachments.vue'
 import TaskSubmissions from './TaskSubmissions.vue'
 import { taskService, type Task, type ProductionNote, type TaskAttachment, type Submission } from '@/services/task'
 import { projectService, type ProjectMember } from '@/services/project'
+import { useDepartmentsStore } from '@/stores/departments'
 import { useAuthStore } from '@/stores/auth'
 import { useToast } from '@/components/ui/toast/use-toast'
 
@@ -358,6 +374,7 @@ const emit = defineEmits<{
 const { toast } = useToast()
 const authStore = useAuthStore()
 const { isCoordinatorOrAdmin } = usePermission()
+const departmentsStore = useDepartmentsStore()
 
 const task = ref<Task | null>(null)
 const loading = ref(false)
@@ -365,6 +382,7 @@ const error = ref<string | null>(null)
 const localStatus = ref('')
 const localStartDate = ref('')
 const localDeadline = ref('')
+const localDepartment = ref('')
 const notes = ref<ProductionNote[]>([])
 const attachments = ref<TaskAttachment[]>([])
 const submissions = ref<Submission[]>([])
@@ -392,6 +410,15 @@ const canSubmitWork = computed(() => {
 
 const canReassign = computed(() => isCoordinatorOrAdmin.value)
 
+const departmentOptions = computed(() => {
+  if (!task.value) return []
+  return departmentsStore.getAllDepartmentOptions(task.value.project_id)
+})
+
+function formatDepartment(department: string): string {
+  return department.replace(/_/g, ' ').replace(/^\w/, c => c.toUpperCase())
+}
+
 async function loadTask() {
   loading.value = true
   error.value = null
@@ -400,6 +427,8 @@ async function loadTask() {
     localStatus.value = task.value.status
     localStartDate.value = task.value.start_date || ''
     localDeadline.value = task.value.deadline || ''
+    localDepartment.value = task.value.department || ''
+    departmentsStore.fetchProjectDepartments(task.value.project_id)
   } catch (err: any) {
     console.error('Error loading task:', err)
     error.value = err.response?.data?.detail || 'Failed to load task'
@@ -483,6 +512,30 @@ async function handleDateChange(field: 'start_date' | 'deadline', value: string)
   }
 }
 
+async function handleDepartmentChange(value: string) {
+  if (!task.value) return
+
+  const previous = task.value.department
+  try {
+    const updated = await taskService.updateTask(props.taskId, { department: value || null } as any)
+    task.value.department = updated.department
+    localDepartment.value = updated.department || ''
+    emit('taskUpdated')
+    toast({
+      title: 'Success',
+      description: 'Task department updated successfully'
+    })
+  } catch (error: any) {
+    console.error('Error updating department:', error)
+    localDepartment.value = previous || ''
+    toast({
+      title: 'Error',
+      description: error.response?.data?.detail || 'Failed to update task department',
+      variant: 'destructive'
+    })
+  }
+}
+
 async function handleQuickAction(action: 'start' | 'submit') {
   if (!task.value) return