feat(ST-vi5iff4s): SoloTask-interface + Prisma-queries uitbreiden met PBI-velden (#116)

pbi_code, pbi_title, pbi_description (nullable) toegevoegd aan SoloTask-interface.
Desktop en mobile solo-page: story.pbi select + mapping via ?. en ?? null.
Test-fixtures bijgewerkt (3 bestanden). 72 testfiles groen, tsc + build slagen.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

__tests__/components/solo/solo-board-batch-enqueue.test.tsx

@@ -94,6 +94,9 @@ const TODO_TASK = {
   story_code: 'ST-1',
   story_title: 'Story 1',
   task_code: 'ST-1.1',
+  pbi_code: null,
+  pbi_title: null,
+  pbi_description: null,
 }
 
 const DEFAULT_PROPS = {

__tests__/components/solo/task-detail-dialog.test.tsx

@@ -65,6 +65,9 @@ const baseTask: SoloTask = {
   story_code: 'ST-100',
   story_title: 'Test Story',
   task_code: 'ST-100.1',
+  pbi_code: null,
+  pbi_title: null,
+  pbi_description: null,
 }
 
 const DEFAULT_PROPS = {

__tests__/stores/solo-store-realtime.test.ts

@@ -17,6 +17,9 @@ const baseTask = (id: string, overrides: Partial<SoloTask> = {}): SoloTask => ({
   story_code: 'ST-100',
   story_title: 'Original Story',
   task_code: 'ST-100.1',
+  pbi_code: null,
+  pbi_title: null,
+  pbi_description: null,
   ...overrides,
 })