fix: UX improvements for German association users

- fix(member-detail): display gender in German (Männlich/Weiblich/Divers)
  instead of raw English enum values (male/female/diverse)

- fix(member-detail): display country names in German (Österreich, Deutschland)
  instead of raw ISO codes (AT, DE)

- fix(member-statistics): total member count was always 0
  getStatistics() returns per-status counts without a total key;
  now computes total by summing all status counts

- fix(i18n): add 56 breadcrumb segment translations for DE and EN
  Breadcrumbs were showing English path segments (Courses, Calendar,
  Registrations) because translation keys for URL path segments were
  missing. Added all segment-level route translations so breadcrumbs
  now display in German throughout the app.

packages/features/member-management/src/components/member-detail-tabs.tsx

@@ -158,7 +158,11 @@ export function MemberDetailTabs({
                 />
                 <DetailRow
                   label="Geschlecht"
-                  value={String(member.gender ?? '—')}
+                  value={
+                    member.gender
+                      ? { male: 'Männlich', female: 'Weiblich', diverse: 'Divers' }[member.gender as string] ?? String(member.gender)
+                      : '—'
+                  }
                 />
               </CardContent>
             </Card>
@@ -211,7 +215,18 @@ export function MemberDetailTabs({
                 />
                 <DetailRow
                   label="Land"
-                  value={String(member.country ?? 'DE')}
+                  value={
+                    (() => {
+                      const code = String(member.country ?? 'DE');
+                      const countries: Record<string, string> = {
+                        DE: 'Deutschland', AT: 'Österreich', CH: 'Schweiz',
+                        LI: 'Liechtenstein', LU: 'Luxemburg', IT: 'Italien',
+                        FR: 'Frankreich', NL: 'Niederlande', BE: 'Belgien',
+                        PL: 'Polen', CZ: 'Tschechien', DK: 'Dänemark',
+                      };
+                      return countries[code] ?? code;
+                    })()
+                  }
                 />
               </CardContent>
             </Card>