feat: Global-Admin Org-Switcher fuer info@aegis-sight.de

Ermoeglicht dem Global Admin (is_global_admin Flag) zwischen
Organisationen zu wechseln. Neue Endpoints: GET /api/auth/organizations,
POST /api/auth/switch-org. Org-Dropdown im Header-Menue, nur fuer
Global Admin sichtbar. Komplett herausnehmbar (Flag + Code-Bloecke).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/static/js/api.js

@@ -243,4 +243,13 @@ const API = {
             headers: { 'Authorization': `Bearer ${token}` },
         });
     },
+
+    // --- Global Admin: Org-Wechsel (herausnehmbar) ---
+    listOrganizations() {
+        return this._request('GET', '/auth/organizations');
+    },
+
+    switchOrg(organizationId) {
+        return this._request('POST', '/auth/switch-org', { organization_id: organizationId });
+    },
 };