fix(articles): article ROT/RUT prefill was dead for every dashboard-created article (#1651)

* fix(articles): article ROT/RUT prefill was dead for every dashboard-created article

Follow-up to #1634. The user re-tested and picking a RUT article still left
the line on "Ingen": the article form has always stored the bare kind
('ROT'/'RUT'), while the prefill only recognised Skatteverket work-type codes
(BYGG, STAD, ...). On prod every dashboard-created ROT/RUT article holds the
bare kind, so the fix in #1634 never fired for a real user, and worse, since
the helper returned null for those values, picking such an article CLEARED a
deduction the user had set manually on the row.

- rot-rut-rules: parseArticleHouseworkType() understands both vocabularies
  (code -> kind + arbetstyp; bare ROT/RUT -> kind only), plus
  normalizeHouseworkType()/HOUSEWORK_TYPE_VALUES/workTypeLabel().
- InvoiceEditor.applyArticle: kind-only articles pre-fill the deduction and
  keep a same-kind arbetstyp already chosen on the row; "Spara som artikel"
  round-trips the code or, lacking one, the kind.
- ArticleForm: the ROT/RUT select now offers the real Skatteverket arbetstyper
  in ROT/RUT groups (its own hint always promised "förifyller arbetstyp");
  legacy kind-only values stay selectable as "RUT (arbetstyp ej vald)" so an
  edit never silently drops the flag. Article detail renders "RUT · Städning"
  instead of the raw code.
- API + MCP commit schemas normalize housework_type (case-insensitive code or
  ROT/RUT, '' clears) and reject anything else; the CSV article import
  normalizes the column the same way. Prod holds 178 articles with '0'/'1'
  from a boolean "Rot" column that the keyword detector mapped straight
  through; those now read as no flag everywhere and can no longer be created.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(articles): review follow-ups on #1651

- InvoiceEditor: switching a row's skattereduktion ROT<->RUT clears an
  arbetstyp from the other list, and Spara som artikel only round-trips a
  work type that belongs to the row's kind (CodeRabbit).
- MCP update_article: null / '' / whitespace now clear housework_type
  (commit drops only undefined keys, so the old undefined mapping made the
  flag un-clearable); create keeps treating them as unset. Tests.
- Article CSV import warns when a non-empty ROT/RUT value is dropped as
  not-an-arbetstyp instead of dropping it silently. Test.
- Hint wording: arbetstyp is pre-filled only when the article carries one.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

app/(dashboard)/articles/[id]/page.tsx

@@ -20,6 +20,7 @@ import { DestructiveConfirmDialog, useDestructiveConfirm } from '@/components/ui
 import { ArrowLeft, Loader2, Lock } from 'lucide-react'
 import { useCanWrite } from '@/lib/hooks/use-can-write'
 import { formatCurrency } from '@/lib/utils'
+import { parseArticleHouseworkType, workTypeLabel } from '@/lib/invoices/rot-rut-rules'
 import type { Article, ArticleType, CreateArticleInput } from '@/types'
 
 const ARTICLE_TYPE_KEY: Record<ArticleType, string> = {
@@ -206,6 +207,15 @@ export default function ArticleDetailPage({
 
   if (!article) return null
 
+  // "RUT · Städning" for a work-type code, "RUT" for a legacy kind-only row,
+  // nothing for values that are not a housework flag (mis-mapped imports).
+  const houseworkDisplay = (() => {
+    const { deductionType, workType } = parseArticleHouseworkType(article.housework_type)
+    if (!deductionType) return null
+    const label = workTypeLabel(workType)
+    return label ? `${deductionType.toUpperCase()} · ${label}` : deductionType.toUpperCase()
+  })()
+
   return (
     <div className="max-w-2xl space-y-8 stagger-enter">
       {/* Header: serif name over a quiet type/status kicker, quiet actions right */}
@@ -307,8 +317,8 @@ export default function ArticleDetailPage({
             <span className="text-muted-foreground">{t('revenue_account_auto')}</span>
           )}
         </DefRow>
-        {article.type === 'tjanst' && article.housework_type && (
-          <DefRow label={t('label_housework')}>{article.housework_type}</DefRow>
+        {article.type === 'tjanst' && houseworkDisplay && (
+          <DefRow label={t('label_housework')}>{houseworkDisplay}</DefRow>
         )}
       </DetailSection>