feat: Multi-URL Document Check with full checklist visibility

New "Dokumenten-Pruefung" tab in Compliance Agent:
- User adds multiple URLs with document type (DSI, AGB, Impressum, Cookie, Widerruf)
- Each document loaded via Playwright, accordions expanded, text extracted
- Checked against type-specific legal checklist
- Optional: Cookie banner check via checkbox

Checklisten-UX (solves "100% looks like nothing was checked"):
- All checks shown per document: green checkmark + matched text excerpt
- Red X for missing fields with legal reference
- Builds user trust: "9 Punkte geprueft, alle bestanden"
- Expandable per document with completeness bar

New checklists:
- Impressum: §5 TMG (6 fields: name, address, contact, register, VAT, representative)
- Cookie-Richtlinie: §25 TDDDG (5 fields: types, purposes, retention, third-party, opt-out)

Backend:
- POST /agent/doc-check — async with polling (same pattern as /scan)
- DocCheckResult includes checks[] with passed/failed + matched_text
- dsi_document_checker returns all_checks in SCORE finding
- Email report shows per-document checklist

Files: agent_doc_check_routes.py (280 LOC), DocCheckTab.tsx (248 LOC),
ChecklistView.tsx (130 LOC), dsi_document_checker.py (+70 LOC)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

admin-compliance/app/api/sdk/v1/agent/doc-check/route.ts

@@ -0,0 +1,39 @@
+/**
+ * Agent Doc-Check Proxy — Multi-URL document verification
+ * POST: start check, GET: poll status
+ */
+
+import { NextRequest, NextResponse } from 'next/server'
+
+const BACKEND_URL = process.env.BACKEND_API_URL || 'http://backend-compliance:8002'
+
+export async function POST(request: NextRequest) {
+  try {
+    const body = await request.text()
+    const response = await fetch(`${BACKEND_URL}/api/compliance/agent/doc-check`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body,
+      signal: AbortSignal.timeout(30000),
+    })
+    const data = await response.json()
+    return NextResponse.json(data, { status: response.status })
+  } catch (error) {
+    return NextResponse.json({ error: 'Pruefung konnte nicht gestartet werden' }, { status: 503 })
+  }
+}
+
+export async function GET(request: NextRequest) {
+  const checkId = request.nextUrl.searchParams.get('check_id')
+  if (!checkId) return NextResponse.json({ error: 'check_id required' }, { status: 400 })
+  try {
+    const response = await fetch(
+      `${BACKEND_URL}/api/compliance/agent/doc-check/${checkId}`,
+      { signal: AbortSignal.timeout(10000) },
+    )
+    const data = await response.json()
+    return NextResponse.json(data)
+  } catch {
+    return NextResponse.json({ error: 'Status-Abfrage fehlgeschlagen' }, { status: 503 })
+  }
+}