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>

lib/idea-prompts/make-plan.md

@@ -102,7 +102,7 @@ stories:
           2. Test toevoegen Y
           3. Verifieer Z
         # task.priority is optioneel en wordt door materialize GENEGEERD.
-        # Tasks erven story.priority; sort_order = positie in deze tasks-array.
+        # Tasks erven story.priority; sort_order wordt afgeleid van de auto-code.
         verify_required: ALIGNED_OR_PARTIAL  # ALIGNED | ALIGNED_OR_PARTIAL | ANY
         verify_only: false                    # true voor pure verify-passes
       - title: "Taak B"
@@ -146,9 +146,9 @@ Beschrijf:
 - `pbi.priority`, `story.priority`: integer 1–4, **verplicht**.
 - `task.priority`: integer 1–4, **optioneel**. **Wordt door materialize genegeerd**
   ten faveure van story-priority — alle tasks binnen een story erven dezelfde
-  priority. Reden: worker sorteert op `priority ASC, sort_order ASC`; gemixte
-  task-priorities zouden de YAML-volgorde verstoren. De YAML-volgorde *is* de
-  execution-volgorde — daar is `sort_order` (positie in de array) voor.
+  priority. `priority` is een **label** (urgentie), géén sorteerkriteria voor stories
+  of taken. De **YAML-array-volgorde** is de execution-volgorde: de server berekent
+  `sort_order = parseCodeNumber(auto-code)` op basis van aanroep-volgorde.
 - Minimaal 1 story; per story minimaal 1 taak.
 - `implementation_plan`: max 8000 chars.
 - `verify_required`: enum exact `ALIGNED` | `ALIGNED_OR_PARTIAL` | `ANY`.