feat(codes): UI toont en accepteert code voor taken

- TaskDialog: code-input boven titel (font-mono, optional,
  placeholder "auto"), CodeBadge in dialog header bij edit
- EditTaskLoader: select code uit DB voor de dialog
- Solo page: vervang inline deriveTaskCode-logica door directe
  task.code uit DB
- Sprint page + TaskList + SprintBoardClient: Task-type krijgt
  verplicht code-veld; TaskList laat ongebruikte storyCode prop
  vallen omdat code-derivatie niet meer nodig is

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -72,26 +72,21 @@ export default async function SoloProductPage({ params }: Props) {
     }),
   ])
 
-  const tasks: SoloTask[] = rawTasks.map(t => {
-    const positionInStory = t.story.tasks.findIndex(st => st.id === t.id)
-    const taskCode =
-      t.story.code && positionInStory >= 0 ? `${t.story.code}.${positionInStory + 1}` : null
-    return {
-      id: t.id,
-      title: t.title,
-      description: t.description,
-      implementation_plan: t.implementation_plan,
-      priority: t.priority,
-      sort_order: t.sort_order,
-      status: t.status as SoloTask['status'],
-      verify_only: t.verify_only,
-      verify_required: t.verify_required as SoloTask['verify_required'],
-      story_id: t.story.id,
-      story_code: t.story.code,
-      story_title: t.story.title,
-      task_code: taskCode,
-    }
-  })
+  const tasks: SoloTask[] = rawTasks.map(t => ({
+    id: t.id,
+    title: t.title,
+    description: t.description,
+    implementation_plan: t.implementation_plan,
+    priority: t.priority,
+    sort_order: t.sort_order,
+    status: t.status as SoloTask['status'],
+    verify_only: t.verify_only,
+    verify_required: t.verify_required as SoloTask['verify_required'],
+    story_id: t.story.id,
+    story_code: t.story.code,
+    story_title: t.story.title,
+    task_code: t.code,
+  }))
 
   const unassignedStories: UnassignedStory[] = rawUnassigned.map(s => ({
     id: s.id,

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

@@ -81,6 +81,7 @@ export default async function SprintBoardPage({ params, searchParams }: Props) {
   for (const story of sprintStories) {
     tasksByStory[story.id] = story.tasks.map(t => ({
       id: t.id,
+      code: t.code,
       title: t.title,
       description: t.description,
       priority: t.priority,