feat(ST-1112): add Suspense skeleton for edit-mode task loading

Extracts task fetch into EditTaskLoader (async server component) so
the sprint board renders immediately while the task loads.
TaskDialogSkeleton shows 3 grey bars during the fetch. Invalid or
out-of-scope task IDs redirect to closePath.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/(app)/products/[id]/sprint/page.tsx

@@ -1,14 +1,15 @@
+import { Suspense } from 'react'
 import { notFound, redirect } from 'next/navigation'
 import { getSession } from '@/lib/auth'
 import { getAccessibleProduct } from '@/lib/product-access'
-import { productAccessFilter } from '@/lib/product-access'
 import { prisma } from '@/lib/prisma'
 import { SprintBoardClient } from '@/components/sprint/sprint-board-client'
 import { SprintHeader } from '@/components/sprint/sprint-header'
 import type { SprintStory, PbiWithStories, ProductMember } from '@/components/sprint/sprint-backlog'
 import type { Task } from '@/components/sprint/task-list'
 import { TaskDialog } from '@/app/_components/tasks/task-dialog'
-import type { TaskDialogTask } from '@/app/_components/tasks/task-dialog'
+import { EditTaskLoader } from '@/app/_components/tasks/edit-task-loader'
+import { TaskDialogSkeleton } from '@/app/_components/tasks/task-dialog-skeleton'
 import Link from 'next/link'
 
 interface Props {
@@ -116,30 +117,6 @@ export default async function SprintBoardPage({ params, searchParams }: Props) {
   const isDemo = session.isDemo ?? false
   const closePath = `/products/${id}/sprint`
 
-  // Fetch task for edit mode (auth-scoped)
-  let editTaskData: TaskDialogTask | null = null
-  if (editTask) {
-    const t = await prisma.task.findFirst({
-      where: {
-        id: editTask,
-        story: { product: productAccessFilter(session.userId) },
-      },
-      select: {
-        id: true,
-        title: true,
-        description: true,
-        implementation_plan: true,
-        priority: true,
-        status: true,
-        created_at: true,
-      },
-    })
-    if (!t) redirect(closePath)
-    editTaskData = t
-  }
-
-  const showDialog = !!newTask || !!editTaskData
-
   return (
     <div className="flex flex-col h-full">
       <SprintHeader
@@ -170,15 +147,26 @@ export default async function SprintBoardPage({ params, searchParams }: Props) {
         </Link>
       </div>
 
-      {showDialog && (
+      {newTask && (
         <TaskDialog
-          task={editTaskData ?? undefined}
           storyId={storyIdParam}
           productId={id}
           closePath={closePath}
           isDemo={isDemo}
         />
       )}
+
+      {editTask && !newTask && (
+        <Suspense fallback={<TaskDialogSkeleton />}>
+          <EditTaskLoader
+            taskId={editTask}
+            userId={session.userId}
+            productId={id}
+            closePath={closePath}
+            isDemo={isDemo}
+          />
+        </Suspense>
+      )}
     </div>
   )
 }

app/_components/tasks/edit-task-loader.tsx

@@ -0,0 +1,47 @@
+import { redirect } from 'next/navigation'
+import { prisma } from '@/lib/prisma'
+import { productAccessFilter } from '@/lib/product-access'
+import { TaskDialog } from './task-dialog'
+
+interface EditTaskLoaderProps {
+  taskId: string
+  userId: string
+  productId: string
+  closePath: string
+  isDemo: boolean
+}
+
+export async function EditTaskLoader({
+  taskId,
+  userId,
+  productId,
+  closePath,
+  isDemo,
+}: EditTaskLoaderProps) {
+  const task = await prisma.task.findFirst({
+    where: {
+      id: taskId,
+      story: { product: productAccessFilter(userId) },
+    },
+    select: {
+      id: true,
+      title: true,
+      description: true,
+      implementation_plan: true,
+      priority: true,
+      status: true,
+      created_at: true,
+    },
+  })
+
+  if (!task) redirect(closePath)
+
+  return (
+    <TaskDialog
+      task={task}
+      productId={productId}
+      closePath={closePath}
+      isDemo={isDemo}
+    />
+  )
+}

app/_components/tasks/task-dialog-skeleton.tsx

@@ -0,0 +1,41 @@
+import { Skeleton } from '@/components/ui/skeleton'
+import { Dialog, DialogContent, DialogTitle } from '@/components/ui/dialog'
+import { cn } from '@/lib/utils'
+
+export function TaskDialogSkeleton() {
+  return (
+    <Dialog open>
+      <DialogContent
+        showCloseButton={false}
+        className={cn(
+          'flex flex-col p-0 gap-0',
+          'max-h-[90vh] w-full max-w-[calc(100%-2rem)]',
+          'sm:max-w-[90vw] sm:max-h-[85vh]',
+          'lg:max-w-[50vw] lg:min-w-[480px]',
+        )}
+      >
+        <DialogTitle className="sr-only">Taak laden…</DialogTitle>
+
+        {/* Header */}
+        <div className="px-6 pt-5 pb-4 border-b border-outline-variant shrink-0">
+          <Skeleton className="h-7 w-40" />
+        </div>
+
+        {/* Body — 3 bars mimicking title + description + plan */}
+        <div className="flex-1 px-6 py-6 space-y-6">
+          <Skeleton className="h-14 w-full" />
+          <Skeleton className="h-24 w-full" />
+          <Skeleton className="h-32 w-full" />
+        </div>
+
+        {/* Footer */}
+        <div className="border-t border-outline-variant px-6 py-4 shrink-0">
+          <div className="flex justify-end gap-2">
+            <Skeleton className="h-8 w-24" />
+            <Skeleton className="h-8 w-24" />
+          </div>
+        </div>
+      </DialogContent>
+    </Dialog>
+  )
+}