feat(PBI-75): sprint task-edit client-side via workspace-store (#183)

Klik op een taak in het sprint-scherm opent de edit-dialog nu
client-side via setActiveTask op de sprint-workspace-store.
Geen URL-navigatie, geen volledige server re-render — alleen
GET /api/tasks/{id} voor het detail. SSE propageert server-saves
automatisch terug.

- TaskDialog: optionele onClose/onSaved callbacks (closePath
  optional gemaakt — backwards compatible)
- SprintTaskDialogMount: nieuwe client-component die
  selectActiveTask consumeert en TaskDialog rendert
- SprintUrlTaskSync: deeplink (?editTask=<id>) → store
- Sprint page: mounts toegevoegd, editTask searchParam +
  EditTaskLoader-Suspense verwijderd
- TaskList.openEditDialog roept setActiveTask aan ipv router.push
- Vitest integratie-test voor SprintTaskDialogMount

Out-of-scope (follow-up PBIs): newTask-flow, mobile, product-backlog.

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

__tests__/components/sprint/sprint-task-dialog-mount.test.tsx

@@ -0,0 +1,119 @@
+// @vitest-environment jsdom
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { render, screen, fireEvent, waitFor } from '@testing-library/react'
+
+vi.mock('next/navigation', () => ({ useRouter: () => ({ push: vi.fn() }) }))
+vi.mock('@/actions/tasks', () => ({
+  saveTask: vi.fn(),
+  deleteTask: vi.fn(),
+}))
+vi.mock('sonner', () => ({ toast: { success: vi.fn(), error: vi.fn() } }))
+
+import { SprintTaskDialogMount } from '@/components/sprint/sprint-task-dialog-mount'
+import { useSprintWorkspaceStore } from '@/stores/sprint-workspace/store'
+import type { SprintWorkspaceTaskDetail } from '@/stores/sprint-workspace/types'
+
+const TASK_DETAIL: SprintWorkspaceTaskDetail = {
+  id: 't1',
+  code: 'T-1',
+  title: 'Mijn taak',
+  description: 'Beschrijving',
+  priority: 2,
+  sort_order: 1,
+  status: 'in_progress',
+  story_id: 'story-1',
+  sprint_id: 'sprint-1',
+  created_at: new Date('2026-01-15'),
+  _detail: true,
+  implementation_plan: 'Stap 1\nStap 2',
+}
+
+function resetStore() {
+  useSprintWorkspaceStore.setState((s) => {
+    s.context.activeProduct = null
+    s.context.activeSprintId = null
+    s.context.activeStoryId = null
+    s.context.activeTaskId = null
+    s.entities.sprintsById = {}
+    s.entities.storiesById = {}
+    s.entities.tasksById = {}
+    s.relations.sprintIdsByProduct = {}
+    s.relations.storyIdsBySprint = {}
+    s.relations.taskIdsByStory = {}
+    s.loading.loadedProductSprintsIds = {}
+    s.loading.loadingProductId = null
+    s.loading.loadedSprintIds = {}
+    s.loading.loadingSprintId = null
+    s.loading.loadedStoryIds = {}
+    s.loading.loadedTaskIds = {}
+    s.loading.activeRequestId = null
+    s.pendingMutations = {}
+  })
+}
+
+beforeEach(() => {
+  resetStore()
+})
+
+afterEach(() => {
+  vi.restoreAllMocks()
+})
+
+describe('SprintTaskDialogMount', () => {
+  it('rendert niets wanneer er geen active task is', () => {
+    const { container } = render(
+      <SprintTaskDialogMount productId="p1" isDemo={false} />,
+    )
+    expect(container.textContent).toBe('')
+  })
+
+  it('rendert niets wanneer active task geen _detail heeft', () => {
+    useSprintWorkspaceStore.setState((s) => {
+      s.entities.tasksById['t1'] = {
+        id: 't1',
+        code: 'T-1',
+        title: 'Mijn taak',
+        description: null,
+        priority: 2,
+        sort_order: 1,
+        status: 'todo',
+        story_id: 'story-1',
+        sprint_id: 'sprint-1',
+        created_at: new Date(),
+      }
+      s.context.activeTaskId = 't1'
+    })
+
+    const { container } = render(
+      <SprintTaskDialogMount productId="p1" isDemo={false} />,
+    )
+    expect(container.textContent).toBe('')
+  })
+
+  it('rendert TaskDialog met titel "Taak bewerken" wanneer detail aanwezig is', () => {
+    useSprintWorkspaceStore.setState((s) => {
+      s.entities.tasksById['t1'] = TASK_DETAIL
+      s.context.activeTaskId = 't1'
+    })
+
+    render(<SprintTaskDialogMount productId="p1" isDemo={false} />)
+
+    expect(screen.getByText('Taak bewerken')).toBeTruthy()
+    expect((screen.getByLabelText(/Titel/) as HTMLInputElement).value).toBe('Mijn taak')
+  })
+
+  it('clear activeTaskId wanneer Annuleren wordt geklikt', async () => {
+    useSprintWorkspaceStore.setState((s) => {
+      s.entities.tasksById['t1'] = TASK_DETAIL
+      s.context.activeTaskId = 't1'
+    })
+
+    render(<SprintTaskDialogMount productId="p1" isDemo={false} />)
+
+    fireEvent.click(screen.getByRole('button', { name: 'Annuleren' }))
+
+    await waitFor(() => {
+      expect(useSprintWorkspaceStore.getState().context.activeTaskId).toBeNull()
+    })
+  })
+})