fix(reports): valid two-file NE-bilaga SRU submission (#318, #319) (#844)

* fix(reports): generate valid two-file NE-bilaga SRU submission (#318, #319)

The NE-bilaga "Ladda ner SRU" export produced a file Skatteverket rejects: it
was served as UTF-8 text/plain (å/ä/ö mojibake, #319) and was structurally
invalid — a single blob with #PRODUKT KONTROLLUPPGIFTER (the KU code), no
INFO.SRU/BLANKETTER.SRU split, a #SKAPAT typo, no #FIL_SLUT, and suspect field
codes 7310–7350 (#318).

Rewrite the generator to mirror the working INK2 generator: a two-file
INFO.SRU + BLANKETTER.SRU submission, ISO 8859-1 encoded and zipped, with
#PRODUKT SRU, #DATABESKRIVNING_*/#MEDIELEV_*, #BLANKETT NE-<år>P<x>,
#IDENTITET <personnummer12> <date> <time>, and #FIL_SLUT. Field codes use the
authoritative BAS NE_EJ_K1 coupling table (R1→7400 … R10→7505, R11→7440;
period dates 7011/7012). Enskild-firma identity is the owner's 12-digit
personnummer (birth-century prefix, not INK2's juridisk-person "16").

- Extract the shared ISO-8859-1 encoder to lib/reports/sru-encoding.ts (was
  inline in the INK2 route).
- Extend the NE engine/types to carry address/postort/email for INFO.SRU.
- Frontend: NE SRU download uses the INK2 blob pattern; fix a pre-existing
  param bug in EfDeclarationSection (fiscal_period_id → period_id, +format=sru).
- Add generator tests (structure, BAS field codes, zero-omission, ISO-8859-1).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(reports): address review feedback on NE-bilaga SRU generator (#318)

- getZipFilename uses the income year (fiscal year END) so the filename matches
  the blankett type/identity for broken fiscal years.
- Refuse to generate a submission when the personnummer is missing/invalid
  (compute + validate the 12-digit identity once in generateNESRUSubmission and
  throw) instead of silently emitting a placeholder #IDENTITET that Skatteverket
  would reject after upload.
- validateBlanketterSru now asserts the mandatory räkenskapsår date fields
  (#UPPGIFT 7011/7012) — their absence is a level-2 rejection.
- 10-digit personnummer century is inferred from adult age (≥18, <110) at the
  income year, fixing the e.g. 1924-born/yy=24 edge that mapped to 2024.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

components/bookkeeping/year-end/EfDeclarationSection.tsx

@@ -361,11 +361,11 @@ export function EfDeclarationSection({
         <CardContent>
           <Button asChild variant="outline">
             <Link
-              href={`/api/reports/ne-bilaga?fiscal_period_id=${fiscalPeriodId}`}
+              href={`/api/reports/ne-bilaga?period_id=${fiscalPeriodId}&format=sru`}
               prefetch={false}
             >
               <FileDown className="mr-2 h-4 w-4" />
-              Förhandsgranska NE-bilaga
+              Ladda ner NE-bilaga (SRU)
             </Link>
           </Button>
         </CardContent>

components/reports/NEDeclarationView.tsx

@@ -12,6 +12,7 @@ import { formatCurrency } from '@/lib/utils'
 export function NEDeclarationView({ periodId }: { periodId: string }) {
   const [data, setData] = useState<NEDeclaration | null>(null)
   const [loading, setLoading] = useState(false)
+  const [downloading, setDownloading] = useState(false)
   const [error, setError] = useState<string | null>(null)
 
   const fetchDeclaration = async () => {
@@ -32,8 +33,24 @@ export function NEDeclarationView({ periodId }: { periodId: string }) {
     }
   }
 
-  const downloadSRU = () => {
-    window.open(`/api/reports/ne-bilaga?period_id=${periodId}&format=sru`, '_blank')
+  const downloadSRU = async () => {
+    setDownloading(true)
+    try {
+      const res = await fetch(`/api/reports/ne-bilaga?period_id=${periodId}&format=sru`)
+      if (!res.ok) throw new Error('Download failed')
+      const blob = await res.blob()
+      const filename = res.headers.get('Content-Disposition')?.match(/filename="(.+)"/)?.[1] || 'NE_SRU.zip'
+      const url = URL.createObjectURL(blob)
+      const a = document.createElement('a')
+      a.href = url
+      a.download = filename
+      a.click()
+      URL.revokeObjectURL(url)
+    } catch {
+      setError('Kunde inte ladda ner SRU-filer')
+    } finally {
+      setDownloading(false)
+    }
   }
 
   // NE ruta labels
@@ -72,9 +89,9 @@ export function NEDeclarationView({ periodId }: { periodId: string }) {
               {loading ? 'Laddar...' : 'Hämta NE-bilaga'}
             </Button>
             {data && (
-              <Button variant="outline" onClick={downloadSRU}>
+              <Button variant="outline" onClick={downloadSRU} disabled={downloading}>
                 <Download className="h-4 w-4 mr-2" />
-                Ladda ner SRU-fil
+                {downloading ? 'Laddar ner...' : 'Ladda ner SRU-fil'}
               </Button>
             )}
           </div>