feat: Projekt-Verwaltung verbessern — Archivieren, Loeschen, Wiederherstellen

- Backend: Restore-Endpoint (POST /projects/{id}/restore) und
  Hard-Delete-Endpoint (DELETE /projects/{id}/permanent) hinzugefuegt
- Frontend: Dreistufiger Dialog (Archivieren / Endgueltig loeschen mit
  Bestaetigungsdialog) statt einfachem Loeschen
- Archivierte Projekte aufklappbar in der Projektliste mit
  Wiederherstellen-Button
- CustomerTypeSelector entfernt (redundant seit Multi-Projekt)
- Default tenantId von 'default' auf UUID geaendert (Backend-400-Fix)
- SQL-Cast :state::jsonb durch CAST(:state AS jsonb) ersetzt (SQLAlchemy-Fix)
- snake_case/camelCase-Mapping fuer Backend-Response (NaN-Datum-Fix)
- projectInfo wird beim Laden vom Backend geholt (Header zeigt Projektname)
- API-Client erzeugt sich on-demand (Race-Condition-Fix fuer Projektliste)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-compliance/app/sdk/page.tsx

@@ -3,9 +3,8 @@
 import React from 'react'
 import Link from 'next/link'
 import { useSDK, SDK_PACKAGES, getStepsForPackage } from '@/lib/sdk'
-import { CustomerTypeSelector } from '@/components/sdk/CustomerTypeSelector'
 import { ProjectSelector } from '@/components/sdk/ProjectSelector/ProjectSelector'
-import type { CustomerType, SDKPackageId } from '@/lib/sdk/types'
+import type { SDKPackageId } from '@/lib/sdk/types'
 
 // =============================================================================
 // DASHBOARD CARDS
@@ -171,6 +170,9 @@ function QuickActionCard({
 export default function SDKDashboard() {
   const { state, packageCompletion, completionPercentage, setCustomerType, projectId } = useSDK()
 
+  // customerType is set during project creation — default to 'new' for legacy projects
+  const effectiveCustomerType = state.customerType || 'new'
+
   // No project selected → show project list
   if (!projectId) {
     return <ProjectSelector />
@@ -180,7 +182,7 @@ export default function SDKDashboard() {
   const totalSteps = SDK_PACKAGES.reduce((sum, pkg) => {
     const steps = getStepsForPackage(pkg.id)
     // Filter import step for new customers
-    return sum + steps.filter(s => !(s.id === 'import' && state.customerType === 'new')).length
+    return sum + steps.filter(s => !(s.id === 'import' && effectiveCustomerType === 'new')).length
   }, 0)
 
   // Calculate stats
@@ -200,19 +202,6 @@ export default function SDKDashboard() {
     return packageCompletion[prevPkg.id] < 100
   }
 
-  // Show customer type selector if not set
-  if (!state.customerType) {
-    return (
-      <div className="min-h-[calc(100vh-200px)] flex items-center justify-center py-12">
-        <CustomerTypeSelector
-          onSelect={(type: CustomerType) => {
-            setCustomerType(type)
-          }}
-        />
-      </div>
-    )
-  }
-
   return (
     <div className="space-y-8">
       {/* Header */}
@@ -220,16 +209,16 @@ export default function SDKDashboard() {
         <div>
           <h1 className="text-2xl font-bold text-gray-900">AI Compliance SDK</h1>
           <p className="mt-1 text-gray-500">
-            {state.customerType === 'new'
+            {effectiveCustomerType === 'new'
               ? 'Neukunden-Modus: Erstellen Sie alle Compliance-Dokumente von Grund auf.'
               : 'Bestandskunden-Modus: Erweitern Sie bestehende Dokumente.'}
           </p>
         </div>
         <button
-          onClick={() => setCustomerType(state.customerType === 'new' ? 'existing' : 'new')}
+          onClick={() => setCustomerType(effectiveCustomerType === 'new' ? 'existing' : 'new')}
           className="text-sm text-purple-600 hover:text-purple-700 underline"
         >
-          {state.customerType === 'new' ? 'Zu Bestandskunden wechseln' : 'Zu Neukunden wechseln'}
+          {effectiveCustomerType === 'new' ? 'Zu Bestandskunden wechseln' : 'Zu Neukunden wechseln'}
         </button>
       </div>
 
@@ -282,7 +271,7 @@ export default function SDKDashboard() {
       </div>
 
       {/* Bestandskunden: Gap Analysis Banner */}
-      {state.customerType === 'existing' && state.importedDocuments.length === 0 && (
+      {effectiveCustomerType === 'existing' && state.importedDocuments.length === 0 && (
         <div className="bg-gradient-to-r from-indigo-50 to-purple-50 border border-indigo-200 rounded-xl p-6">
           <div className="flex items-start gap-4">
             <div className="w-12 h-12 bg-indigo-100 rounded-xl flex items-center justify-center flex-shrink-0">
@@ -348,7 +337,7 @@ export default function SDKDashboard() {
         <div className="grid grid-cols-1 lg:grid-cols-2 xl:grid-cols-3 gap-6">
           {SDK_PACKAGES.map(pkg => {
             const steps = getStepsForPackage(pkg.id)
-            const visibleSteps = steps.filter(s => !(s.id === 'import' && state.customerType === 'new'))
+            const visibleSteps = steps.filter(s => !(s.id === 'import' && effectiveCustomerType === 'new'))
 
             return (
               <PackageCard