Sprint: Stories en taken krijgen één voorspelbare volgorde gekoppeld aan hun code; drag-and-drop herordening voor stories/taken verdwijnt, priority wordt puur label. (#201)

* feat(code): add parseCodeNumber helper to lib/code.ts

Pure helper that extracts the trailing numeric sequence from a code string
(ST-007 → 7, T-42 → 42). Non-conforming codes fall back to Number.MAX_SAFE_INTEGER
so they sort to the end. Includes 5 unit tests.

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

* feat(tasks): add code field to BacklogTask type and all task selects

Adds `code: string | null` to BacklogTask interface and includes it in
all Prisma task.findMany selects (backlog API, stories tasks API, page
hydration routes). Updates coerceTaskPayload and test fixtures to match.

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

* feat(sort-order): derive story/task sort_order from parseCodeNumber(code)

All create paths (createStoryAction, saveTask, createTaskAction,
materializeIdeaPlanAction) and code-edit paths (updateStoryAction, saveTask
update) now set sort_order = parseCodeNumber(code) instead of last+1.
Removes stale last-record queries from create paths.

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

* fix(sort-order): decouple sprint membership actions from sort_order

createSprintAction and addStoryToSprintAction no longer write sort_order
when adding stories to a sprint. sort_order is derived from code via
parseCodeNumber, so membership should only set sprint_id + status.

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

* refactor(ordering): remove priority from all story/task orderBy

Story- en taak-ordering is nu puur sort_order asc (created_at als
tiebreaker). PBI-ordering (priority + sort_order) blijft ongewijzigd.

Gewijzigd: backlog/route, pbis/stories/route, claude-context/route,
next-story/route, workspace/route, tasks/route, sprint-runs (query +
in-memory sort), solo-workspace-server, page.tsx (app + mobile + sprint),
store compareStory, actions/sprints story-query, next-story test.

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

* refactor(dnd): remove drag-and-drop reorder for stories and tasks

- Remove reorderStoriesAction, reorderTasksAction, reorderSprintStoriesAction
- Delete REST route app/api/stories/[id]/tasks/reorder/route.ts
- Remove DnD from backlog story-panel and task-panel (flat list)
- Remove reorder-within-sprint branch from sprint-board-client handleDragEnd
- Switch SortableSprintRow to plain SprintRow using useDraggable (membership drag kept)
- Remove all DnD from task-list (status toggle + edit kept)
- Remove story-order/task-order/sprint-story-order/sprint-task-order mutation types and store handlers
- Remove related tests for deleted reorder route; fix sprint store tests

* feat(backlog): toon code-badge op backlog-taakkaarten

Geeft code={task.code} door aan <BacklogCard> in TaskCard (task-panel.tsx).
BacklogCard rendert de CodeBadge al conditionally — alleen de prop ontbrak.

* feat(migration): backfill story/task sort_order from code numeric suffix

One-time Prisma migration that sets sort_order = trailing numeric part
of code for all existing stories and tasks, consistent with
parseCodeNumber (fallback = Number.MAX_SAFE_INTEGER for non-conforming
codes). PBIs are intentionally excluded.

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

* docs+tests(sort-order): update for code-binding order on stories/tasks

- Rewrite docs/patterns/sort-order.md: float-insertion PBI only; story/task
  sort_order = parseCodeNumber(code), never drag/membership mutated
- Update plan-to-pbi-flow.md: sort_order auto, sprint_id param, priority=label
- Update make-plan.md: priority=label, array order = execution order
- Update rest-contract.md: fix sprint-tasks ordering, remove reorder endpoint
- Add ADR-0011: code is bindende volgordesleutel voor stories/taken
- Regenerate docs/INDEX.md via npm run docs
- Remove reorderStoriesAction/reorderTasksAction mocks from backlog tests
- Remove dnd-kit mocks from task-panel test (panel no longer uses dnd)
- Extend materializeIdeaPlanAction test: assert sort_order=parseCodeNumber(code)

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

---------

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

docs/api/rest-contract.md

@@ -169,7 +169,7 @@ Hoogst geprioriteerde open story in de actieve sprint.
 
 ### `GET /api/sprints/:id/tasks`
 
-Lijst taken van de sprint, geordend op `(story.sort_order, task.priority, task.sort_order)`.
+Lijst taken van de sprint, geordend op `(story.sort_order, task.sort_order)` — code-volgorde, geen priority.
 
 **Query params:** `?limit=N` (default 10, max 50)
 
@@ -193,19 +193,6 @@ Lijst taken van de sprint, geordend op `(story.sort_order, task.priority, task.s
 
 ---
 
-### `PATCH /api/stories/:id/tasks/reorder`
-
-Volgorde van taken binnen een story aanpassen.
-
-**Body:**
-```json
-{ "task_ids": ["task-id-a", "task-id-b", "task-id-c"] }
-```
-
-Alle IDs moeten bij de story horen. **Foutcodes:** `422` bij Zod-fouten of als een task_id niet tot de story behoort.
-
----
-
 ### `PATCH /api/tasks/:id`
 
 Status of implementation_plan bijwerken. Minstens één van beide is verplicht.
@@ -537,7 +524,7 @@ worden. Tot dan retourneert de stub-default in vitest een lege response.
 |---|---|---|---|
 | `ensureProductLoaded(productId)` | `GET /api/products/:id/backlog` | **ontbreekt** | T-870 (Story 7) |
 | `ensurePbiLoaded(pbiId)` | `GET /api/pbis/:id/stories` | **ontbreekt** (en `/api/pbis` route-folder bestaat nog niet) | T-870 (Story 7) |
-| `ensureStoryLoaded(storyId)` | `GET /api/stories/:id/tasks` | **ontbreekt** (alleen `tasks/reorder` bestaat) | T-870 (Story 7) |
+| `ensureStoryLoaded(storyId)` | `GET /api/stories/:id/tasks` | **ontbreekt** | T-870 (Story 7) |
 | `ensureTaskLoaded(taskId)` | `GET /api/tasks/:id` | **ontbreekt** (alleen `PATCH` bestaat) | T-870 (Story 7) |
 
 Vereisten voor de toe te voegen routes: