feat: move configuration from .env to DB with Admin UI management

Replace hardcoded .env configuration with database-backed settings
manageable through the Admin web interface. This reduces .env to
bootstrap-only variables (DB, Keycloak, encryption keys).

Backend:
- Add SystemSetting Prisma model with category, valueType, isSecret
- Add system-settings NestJS module (CRUD, 60s cache, encryption)
- Refactor all 7 connectors to lazy-load credentials from DB via
  CredentialsService.findActiveByType() instead of ConfigService
- Add event-driven credential reload (@nestjs/event-emitter)
- Dynamic CORS origins and conditional Swagger from DB settings
- Fix JWT strategy: use Keycloak JWKS (RS256) instead of symmetric secret
- Add SYSTEM_SETTINGS_VIEW/MANAGE permissions
- Seed 13 default settings (sync intervals, features, branding, CORS)
- Add env-to-db migration script (prisma/migrate-env-to-db.ts)

Frontend:
- Add use-credentials hook (full CRUD for integration credentials)
- Add use-system-settings hook (read/update system settings)
- Wire admin-integrations page to real API (create/update/test/toggle)
- Add admin system-settings page with 4 tabs (Branding, CORS, Sync, Features)
- Fix sidebar double-highlighting with exactMatch flag
- Fix integration detail fallback when API unavailable
- Fix API client to unwrap backend's {success, data} envelope
- Update NEXT_PUBLIC_API_URL to include /v1 version prefix
- Fix activity-widget hydration error
- Add i18n keys for systemSettings (de + en)

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

apps/web/src/components/layout/sidebar.tsx

@@ -44,6 +44,7 @@ interface NavItem {
   icon: LucideIcon;
   requiredRoles?: UserRole[];
   children?: NavItem[];
+  exactMatch?: boolean;
 }
 
 /** Main navigation structure with role requirements */
@@ -115,6 +116,7 @@ const mainNavItems: NavItem[] = [
         key: 'overview',
         href: '/integrations',
         icon: Plug,
+        exactMatch: true,
       },
       {
         key: 'plentyOne',
@@ -152,6 +154,11 @@ const bottomNavItems: NavItem[] = [
         href: '/admin/integrations',
         icon: Plug,
       },
+      {
+        key: 'systemSettings',
+        href: '/admin/settings',
+        icon: Settings,
+      },
     ],
   },
   {
@@ -209,14 +216,15 @@ export function Sidebar({ locale }: SidebarProps) {
   const filteredMainNav = filterNavItems(mainNavItems, userRoles);
   const filteredBottomNav = filterNavItems(bottomNavItems, userRoles);
 
-  const isActive = (href: string) => {
+  const isActive = (href: string, exactMatch?: boolean) => {
     const localePath = `/${locale}${href}`;
+    if (exactMatch) return pathname === localePath;
     return pathname === localePath || pathname.startsWith(`${localePath}/`);
   };
 
   const isParentActive = (item: NavItem) => {
     if (isActive(item.href)) return true;
-    return item.children?.some((child) => isActive(child.href)) || false;
+    return item.children?.some((child) => isActive(child.href, child.exactMatch)) || false;
   };
 
   return (
@@ -307,7 +315,7 @@ interface NavItemComponentProps {
   item: NavItem;
   locale: string;
   isExpanded: boolean;
-  isActive: (href: string) => boolean;
+  isActive: (href: string, exactMatch?: boolean) => boolean;
   isParentActive: (item: NavItem) => boolean;
   t: (key: string) => string;
 }
@@ -321,7 +329,7 @@ function NavItemComponent({
   t,
 }: NavItemComponentProps) {
   const Icon = item.icon;
-  const active = isActive(item.href);
+  const active = isActive(item.href, item.exactMatch);
   const parentActive = isParentActive(item);
   const hasChildren = item.children && item.children.length > 0;
 
@@ -383,7 +391,7 @@ function NavItemComponent({
               href={`/${locale}${child.href}`}
               className={cn(
                 'rounded px-2 py-1 text-sm transition-colors hover:bg-accent',
-                isActive(child.href) && 'bg-accent font-medium'
+                isActive(child.href, child.exactMatch) && 'bg-accent font-medium'
               )}
             >
               {t(child.key)}
@@ -426,7 +434,7 @@ function NavItemComponent({
         >
           {item.children?.map((child) => {
             const ChildIcon = child.icon;
-            const childActive = isActive(child.href);
+            const childActive = isActive(child.href, child.exactMatch);
 
             return (
               <Link