feat(iace): DSMS-CID-Badge im Tech-File-Export + aggregierter Bulk-Diff

Punkt 1 — UI-CID-Badge nach erfolgreichem Tech-File-Export:
- archiveTechFile setzt X-DSMS-CID / X-DSMS-Filename / X-DSMS-Size response
  headers + Access-Control-Expose-Headers, sobald DSMS-Archive durchlief
- Split iace_handler_techfile.go (war ueber 500 LOC) → archiveTechFile lebt
  jetzt in iace_handler_techfile_archive.go, setDSMSResponseHeaders als
  pure Helper mit 3 unit tests
- Next.js IACE-Proxy forwarded die X-DSMS-* Header und erkennt jetzt auch
  XLSX/DOCX/MD als Binary-Response (vorher nur PDF/ZIP/octet-stream)
- ExportCIDBadge.tsx zeigt CID, Filename, Groesse + Kopieren-Button +
  "Verlauf anzeigen" (oeffnet CIDHistoryModal)

Punkt 2 — Bulk-Diff Report V1 → V_latest:
- Neuer Endpoint GET /api/v1/documents/{cid}/bulk-diff im dsms-gateway:
  laeuft parent_cid-Kette ab, berechnet chronologische Step-Diffs,
  aggregiert Totals (added/removed lines, metadata_fields_changed,
  binary_steps). Edge-Cases: einzelne Version, binaere Steps, abgebrochene
  Kette
- BulkDiffPanel.tsx zeigt 4-Stat-Header + Step-Tabelle
- CIDHistoryModal bekommt Toggle-Button "Bulk-Diff V1 → V_latest anzeigen"
  neben dem Versions-Counter; damit auch vom IACE-Export-Badge erreichbar

Tests: 3 neue Go-Tests, 4 neue pytest-Tests, alle gruen

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

admin-compliance/app/sdk/iace/[projectId]/tech-file/page.tsx

@@ -4,6 +4,7 @@ import React, { useState, useEffect, useRef } from 'react'
 import { useParams } from 'next/navigation'
 import { TechFileEditor } from '@/components/sdk/iace/TechFileEditor'
 import { ReportGenerator } from './_components/ReportGenerator'
+import { ExportCIDBadge, type LastExport } from './_components/ExportCIDBadge'
 import { SECTION_TYPES, STATUS_CONFIG, EXPORT_FORMATS } from './_constants'
 
 interface TechFileSection {
@@ -116,6 +117,7 @@ export default function TechFilePage() {
   const [viewingSection, setViewingSection] = useState<TechFileSection | null>(null)
   const [exporting, setExporting] = useState(false)
   const [showExportMenu, setShowExportMenu] = useState(false)
+  const [lastExport, setLastExport] = useState<LastExport | null>(null)
   const exportMenuRef = useRef<HTMLDivElement>(null)
 
   // Close export menu when clicking outside
@@ -224,6 +226,19 @@ export default function TechFilePage() {
         a.click()
         document.body.removeChild(a)
         window.URL.revokeObjectURL(url)
+
+        // DSMS archive metadata is forwarded by the backend in X-DSMS-* headers
+        // when archiving succeeded. If headers are absent (DSMS gateway down)
+        // the export still works but no badge is shown.
+        const cid = res.headers.get('x-dsms-cid')
+        if (cid) {
+          setLastExport({
+            cid,
+            filename: res.headers.get('x-dsms-filename') || `CE-Akte-${projectId}${extension}`,
+            size: parseInt(res.headers.get('x-dsms-size') || '0', 10) || blob.size,
+            format,
+          })
+        }
       }
     } catch (err) {
       console.error('Failed to export:', err)
@@ -305,6 +320,9 @@ export default function TechFilePage() {
         </div>
       </div>
 
+      {/* DSMS-CID badge nach erfolgreichem Export */}
+      <ExportCIDBadge lastExport={lastExport} onDismiss={() => setLastExport(null)} />
+
       {/* Progress */}
       <div className="bg-white dark:bg-gray-800 rounded-xl border border-gray-200 dark:border-gray-700 p-4">
         <div className="flex items-center justify-between mb-2">