feat(users): add drag-and-drop reordering for PICs

Introduce pic_sort_order to persist custom user ordering
Replace data table with a custom draggable grid layout
Add API endpoint to handle bulk order updates

server/api/admin/users/order.patch.ts

@@ -0,0 +1,24 @@
+import { requireRole } from '../../../utils/auth'
+import { assertBadRequest } from '../../../utils/http'
+import { listUsers, reorderUsers } from '../../../utils/user-repository'
+import { parseUserOrderInput } from '../../../utils/users'
+
+export default defineEventHandler(async (event) => {
+  await requireRole(event, 'super_admin')
+
+  const body = await readBody<{
+    userIds?: unknown
+  }>(event)
+  const { userIds } = parseUserOrderInput(body)
+  const users = await listUsers()
+  const existingIds = new Set(users.map((user) => user.id))
+
+  assertBadRequest(userIds.length === users.length, 'User order must include every user')
+  assertBadRequest(userIds.every((userId) => existingIds.has(userId)), 'User order contains an unknown user')
+
+  await reorderUsers(userIds)
+
+  return {
+    users: await listUsers()
+  }
+})