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>

app/api/reports/ink2/route.ts

@@ -6,6 +6,7 @@ import {
 } from '@/lib/reports/ink2/sru-generator'
 import { withRouteContext } from '@/lib/api/with-route-context'
 import { errorResponseFromCode } from '@/lib/errors/get-structured-error'
+import { encodeISO88591 } from '@/lib/reports/sru-encoding'
 import JSZip from 'jszip'
 
 /**
@@ -67,13 +68,3 @@ export const GET = withRouteContext(
     }
   },
 )
-
-/** Encode a string as ISO 8859-1 bytes; characters outside Latin-1 become '?'. */
-function encodeISO88591(str: string): Uint8Array {
-  const bytes = new Uint8Array(str.length)
-  for (let i = 0; i < str.length; i++) {
-    const code = str.charCodeAt(i)
-    bytes[i] = code <= 0xFF ? code : 0x3F
-  }
-  return bytes
-}

app/api/reports/ne-bilaga/route.ts

@@ -1,12 +1,13 @@
 import { NextResponse } from 'next/server'
 import { generateNEDeclaration } from '@/lib/reports/ne-bilaga/ne-engine'
 import {
-  generateSRUFile,
-  sruFileToString,
-  getSRUFilename,
+  generateNESRUSubmission,
+  getZipFilename,
 } from '@/lib/reports/ne-bilaga/sru-generator'
 import { withRouteContext } from '@/lib/api/with-route-context'
 import { errorResponseFromCode } from '@/lib/errors/get-structured-error'
+import { encodeISO88591 } from '@/lib/reports/sru-encoding'
+import JSZip from 'jszip'
 
 /**
  * GET /api/reports/ne-bilaga
@@ -34,14 +35,23 @@ export const GET = withRouteContext(
       const declaration = await generateNEDeclaration(supabase, companyId!, periodId)
 
       if (format === 'sru') {
-        const sruFile = generateSRUFile(declaration)
-        const sruContent = sruFileToString(sruFile)
-        const filename = getSRUFilename(declaration)
+        const submission = generateNESRUSubmission(declaration)
 
-        return new NextResponse(sruContent, {
+        // Skatteverket requires ISO 8859-1 (Latin-1); UTF-8 mojibakes å/ä/ö and is rejected.
+        const infoBytes = encodeISO88591(submission.infoSru)
+        const blanketterBytes = encodeISO88591(submission.blanketterSru)
+
+        const zip = new JSZip()
+        zip.file('INFO.SRU', infoBytes)
+        zip.file('BLANKETTER.SRU', blanketterBytes)
+
+        const zipArrayBuffer = await zip.generateAsync({ type: 'arraybuffer' })
+        const filename = getZipFilename(declaration)
+
+        return new NextResponse(zipArrayBuffer, {
           status: 200,
           headers: {
-            'Content-Type': 'text/plain; charset=utf-8',
+            'Content-Type': 'application/zip',
             'Content-Disposition': `attachment; filename="${filename}"`,
             'X-Request-Id': requestId,
           },