Add rename and remove for a workspace's placeholder partner

Settings is gaining a partner display, which hides the add-form once a
partner exists. Without these routes a typo'd partner name would be
permanently unfixable, since no endpoint could change or drop one.

PATCH /workspace/{id}/parents/{uuid} renames; DELETE soft-deletes.
Soft rather than hard delete because PersonalData holds PII and the
repository is a SoftDeleteRepository specifically so erasure stays
auditable.

Removal refuses (422) when the member still has leave wishes, planned
leave, parental-leave rows or vacation days, naming the blockers, so a
removal can never orphan plan data. It also refuses for the caller's own
profile, and for a member who has their own login -- the invite/redeem
flow re-points a real user's personal_data into the inviter's workspace,
so soft-deleting that row would silently break their login.

Errors carry message_key + data rather than prose, per the no-Swedish-on
-the-wire rule; NotFoundError/ValidationError gained the same optional
shape DubbeldagError already had, defaulting empty so existing call
sites are unaffected.

Also fixes seed_demo.py constructing WorkspaceService with a stale
3-arg signature, which would have crashed at runtime -- invisible to
pytest since it is a standalone script.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RXMhc9nT6sNz1SL4j8dznL

backend/app/routers/workspace.py

@@ -5,6 +5,7 @@ from uuid import UUID
 from fastapi import APIRouter, HTTPException, status
 
 from app.dependencies import CurrentUserDep, WorkspaceServiceDep
+from app.entities.personal_data import PersonalData
 from app.models.workspace import (
     InvitationResponse,
     InviteResponse,
@@ -20,6 +21,35 @@ from app.utils.errors import InvitationError, NotFoundError, ValidationError
 router = APIRouter(prefix="/api/workspace", tags=["workspace"])
 
 
+def _to_response(pd: PersonalData) -> PersonalDataResponse:
+    return PersonalDataResponse(
+        uuid=pd.uuid,
+        workspace_id=pd.workspace_id,
+        name=pd.name,
+        salary_type=pd.salary_type,
+        employment_status=pd.employment_status,
+        created_at=pd.created_at,
+    )
+
+
+def _to_http_error(exc: NotFoundError | ValidationError) -> HTTPException:
+    """Map a NotFoundError/ValidationError to an HTTPException.
+
+    Both carry an optional `message_key` + `data` pair (§3.5); when present it
+    becomes the structured `detail` so the frontend never has to parse an
+    English sentence. Falls back to the plain message for the (rare) error
+    raised without one.
+    """
+    code = (
+        status.HTTP_404_NOT_FOUND
+        if isinstance(exc, NotFoundError)
+        else status.HTTP_422_UNPROCESSABLE_ENTITY
+    )
+    if exc.message_key:
+        return HTTPException(code, detail={"message_key": exc.message_key, "data": exc.data})
+    return HTTPException(code, detail=str(exc))
+
+
 @router.post("", response_model=WorkspaceResponse, status_code=status.HTTP_201_CREATED)
 async def create_workspace(
     payload: WorkspaceCreate,
@@ -71,17 +101,7 @@ async def list_members(
     _current_user: CurrentUserDep,
 ) -> list[PersonalDataResponse]:
     members = await service.list_members(workspace_id)
-    return [
-        PersonalDataResponse(
-            uuid=m.uuid,
-            workspace_id=m.workspace_id,
-            name=m.name,
-            salary_type=m.salary_type,
-            employment_status=m.employment_status,
-            created_at=m.created_at,
-        )
-        for m in members
-    ]
+    return [_to_response(m) for m in members]
 
 
 @router.post(
@@ -97,16 +117,45 @@ async def add_placeholder_parent(
 ) -> PersonalDataResponse:
     try:
         pd = await service.add_placeholder_parent(workspace_id, payload.display_name)
-    except NotFoundError as exc:
-        raise HTTPException(status.HTTP_404_NOT_FOUND, str(exc)) from exc
-    return PersonalDataResponse(
-        uuid=pd.uuid,
-        workspace_id=pd.workspace_id,
-        name=pd.name,
-        salary_type=pd.salary_type,
-        employment_status=pd.employment_status,
-        created_at=pd.created_at,
-    )
+    except (NotFoundError, ValidationError) as exc:
+        raise _to_http_error(exc) from exc
+    return _to_response(pd)
+
+
+@router.patch(
+    "/{workspace_id}/parents/{personal_data_uuid}",
+    response_model=PersonalDataResponse,
+)
+async def rename_parent(
+    workspace_id: UUID,
+    personal_data_uuid: UUID,
+    payload: PersonalDataCreate,
+    service: WorkspaceServiceDep,
+    _current_user: CurrentUserDep,
+) -> PersonalDataResponse:
+    try:
+        pd = await service.rename_member(workspace_id, personal_data_uuid, payload.display_name)
+    except (NotFoundError, ValidationError) as exc:
+        raise _to_http_error(exc) from exc
+    return _to_response(pd)
+
+
+@router.delete(
+    "/{workspace_id}/parents/{personal_data_uuid}",
+    status_code=status.HTTP_204_NO_CONTENT,
+)
+async def remove_parent(
+    workspace_id: UUID,
+    personal_data_uuid: UUID,
+    service: WorkspaceServiceDep,
+    current_user: CurrentUserDep,
+) -> None:
+    try:
+        await service.remove_member(
+            workspace_id, personal_data_uuid, current_user.personal_data_uuid
+        )
+    except (NotFoundError, ValidationError) as exc:
+        raise _to_http_error(exc) from exc
 
 
 @router.post(