fix: implement 9 production enhancements and security fixes

- Password Complexity: Added 4-level complexity selector (Simple/Moderate/Strong/Very Strong) in admin security settings with dynamic backend validation
- Gallery Security: Removed event date from login page (security risk), replaced with event type badge
- Analytics Config: Fixed "Not Configured" detection logic to check both admin settings and env variables
- Analytics Accuracy: Aligned calculation logic between dashboard and analytics endpoints, added totals verification
- Translations: Added missing activity keys (analytics_settings_updated, cms_page_updated, security_settings_updated, password_reset, admin_logout, system_activity)
- UI Fixes: Fixed German text overflow in CMS page selector with proper CSS truncation
- Date Format: Event creation now respects admin-configured date format instead of browser locale
- Chrome Compatibility: Replaced emoji flags with SVG components for Windows Chrome support

All changes maintain backward compatibility and production stability.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

frontend/src/i18n/locales/de.json

@@ -428,6 +428,12 @@
       "requirePassword": "Passwort für alle Galerien erforderlich",
       "minPasswordLength": "Minimale Passwortlänge",
       "minPasswordLengthHelp": "Mindestanzahl von Zeichen für Galerie-Passwörter",
+      "passwordComplexity": "Passwort-Komplexität",
+      "passwordComplexityHelp": "Sicherheitsstufe für Galerie-Passwörter",
+      "complexitySimple": "Einfach (6+ Zeichen, beliebiger Text)",
+      "complexityModerate": "Moderat (8+ Zeichen, Groß-/Kleinschreibung/Zahlen)",
+      "complexityStrong": "Stark (12+ Zeichen, Groß-/Kleinschreibung/Zahlen)",
+      "complexityVeryStrong": "Sehr stark (12+ Zeichen, alle Zeichentypen)",
       "sessionAuth": "Sitzung & Authentifizierung",
       "sessionTimeout": "Sitzungs-Timeout (Minuten)",
       "sessionTimeoutHelp": "Admin-Sitzungs-Timeout in Minuten",
@@ -721,6 +727,12 @@
       "category_deleted": "Kategorie gelöscht: {{categoryName}}",
       "general_settings_updated": "Allgemeine Einstellungen aktualisiert",
       "favicon_uploaded": "Favicon hochgeladen",
+      "analytics_settings_updated": "Analytik-Einstellungen aktualisiert",
+      "cms_page_updated": "CMS-Seite aktualisiert: {{page}}",
+      "security_settings_updated": "Sicherheitseinstellungen aktualisiert",
+      "password_reset": "Passwort zurückgesetzt für: {{eventName}}",
+      "admin_logout": "Admin {{actorName}} abgemeldet",
+      "system_activity": "Systemaktivität: {{type}}",
       "unknown": "Unbekannte Aktivität"
     }
   },