feat: dashboard widgets, auth fix, profile names, dynamic groups

- Add VehicleDashboardCard: self-contained widget modelled after
  AtemschutzDashboardCard, shows einsatzbereit ratio and inspection
  warnings inline; replaces StatsCard + InspectionAlerts in Dashboard

- Add EquipmentDashboardCard: consolidated equipment status widget
  showing only aggregated counts (no per-item listing); replaces
  EquipmentAlerts component in Dashboard

- Fix auth race condition: add authInitialized flag to api.ts so 401
  responses during initial token validation no longer trigger a
  spurious redirect to /login; save intended destination before login
  redirect and restore it after successful auth callback

- Fix profile firstname/lastname: add extractNames() helper to
  auth.controller.ts that falls back to splitting userinfo.name when
  Authentik does not provide separate given_name/family_name fields;
  applied on both create and update paths

- Dynamic groups endpoint: replace hardcoded KNOWN_GROUPS array in
  events.controller.ts with a DB query (SELECT DISTINCT unnest
  (authentik_groups) FROM users); known slugs get German labels via
  lookup map, unknown slugs are humanized automatically

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

backend/src/services/events.service.ts

@@ -430,6 +430,48 @@ class EventsService {
     return { token, subscribeUrl };
   }
 
+  // -------------------------------------------------------------------------
+  // GROUPS
+  // -------------------------------------------------------------------------
+
+  /**
+   * Returns distinct group slugs from active users as { id, label } pairs.
+   * The label is derived from a known-translations map or humanized from the slug.
+   */
+  async getAvailableGroups(): Promise<Array<{ id: string; label: string }>> {
+    const knownLabels: Record<string, string> = {
+      'dashboard_admin':       'Administratoren',
+      'dashboard_mitglied':    'Mitglieder',
+      'dashboard_fahrmeister': 'Fahrmeister',
+      'dashboard_zeugmeister': 'Zeugmeister',
+      'dashboard_atemschutz':  'Atemschutzwart',
+      'dashboard_jugend':      'Feuerwehrjugend',
+      'dashboard_kommandant':  'Kommandanten',
+      'dashboard_moderator':   'Moderatoren',
+      'feuerwehr-admin':       'Feuerwehr Admin',
+      'feuerwehr-kommandant':  'Feuerwehr Kommandant',
+    };
+
+    const humanizeGroupName = (slug: string): string => {
+      if (knownLabels[slug]) return knownLabels[slug];
+      const stripped = slug.startsWith('dashboard_') ? slug.slice('dashboard_'.length) : slug;
+      const spaced = stripped.replace(/-/g, ' ');
+      return spaced.charAt(0).toUpperCase() + spaced.slice(1);
+    };
+
+    const result = await pool.query(
+      `SELECT DISTINCT unnest(authentik_groups) AS group_name
+       FROM users
+       WHERE is_active = true
+       ORDER BY group_name`
+    );
+
+    return result.rows.map((row) => ({
+      id:    row.group_name as string,
+      label: humanizeGroupName(row.group_name as string),
+    }));
+  }
+
   // -------------------------------------------------------------------------
   // ICAL EXPORT
   // -------------------------------------------------------------------------