fix: hardened security, CSP enforcement, SSRF redirect validation, reenabled S/MIME chain verify, IP spoofing prevention, PDF iframe sandbox

components/files/file-preview-modal.tsx

@@ -223,6 +223,7 @@ export function FilePreviewModal({ name, onClose, onDownload, getFileContent }:
         {!loading && !error && fileType === "pdf" && objectUrl && (
           <iframe
             src={objectUrl}
+            sandbox="allow-same-origin"
             className="w-full max-w-5xl h-full rounded-lg bg-white"
             title={name}
           />

components/layout/navigation-rail.tsx

@@ -169,6 +169,7 @@ export function NavigationRail({
   const sidebarApps = useSettingsStore((s) => s.sidebarApps);
   const showRailAccountList = useSettingsStore((s) => s.showRailAccountList);
   const sidebarAppsEnabled = usePolicyStore((s) => s.isFeatureEnabled('sidebarAppsEnabled'));
+  const filesEnabled = usePolicyStore((s) => s.isFeatureEnabled('filesEnabled'));
   const visibleSidebarApps = sidebarAppsEnabled ? sidebarApps : [];
   const inboxUnread = mailboxes.find(m => m.role === "inbox")?.unreadEmails || 0;
   const [isStalwartAdmin, setIsStalwartAdmin] = useState(false);
@@ -246,7 +247,7 @@ export function NavigationRail({
     { id: "mail", icon: Mail, labelKey: "mail", href: "/", badge: inboxUnread },
     { id: "calendar", icon: Calendar, labelKey: "calendar", href: "/calendar", hidden: !supportsCalendar },
     { id: "contacts", icon: BookUser, labelKey: "contacts", href: "/contacts" },
-    { id: "files", icon: HardDrive, labelKey: "files", href: "/files", hidden: supportsWebDAV === false },
+    { id: "files", icon: HardDrive, labelKey: "files", href: "/files", hidden: supportsWebDAV === false || !filesEnabled },
   ];
 
   const isSettingsActive = !activeAppId && pathname.startsWith("/settings");