feat(legal): imprint & privacy notices, "Über MindSift"

- LEGAL_IMPRINT_/LEGAL_PRIVACY_ URL and Markdown (inline or *_FILE);
  only http(s) URLs accepted
- /auth/status exposes legal info; public GET /legal/{imprint|privacy}
- Links on login/setup screen and in the settings footer: URL opens a new
  tab, Markdown a reading modal; hidden when nothing is configured
- "Über MindSift" modal (version, license, repository) in settings and help
- Docs and compose/env examples

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/settings/UserSettingsView.tsx

@@ -20,11 +20,13 @@ import {
   Pencil,
   Copy,
 } from 'lucide-react';
-import { APIKey, User, UserTheme } from '../../lib/types';
+import { APIKey, AuthStatus, User, UserTheme } from '../../lib/types';
 import { api, triggerHaptic } from '../../lib/api';
 import { customThemeId, ThemeId, ThemeOption } from '../../lib/theme';
 import themeTemplateCss from '../../themes/theme-template.css?raw';
 import { UserAvatar, resizeImageToDataUrl } from '../../components/UserAvatar';
+import { LegalLinks } from '../../components/LegalLinks';
+import { AboutModal } from '../../components/AboutModal';
 
 interface UserSettingsViewProps {
   currentUser: User;
@@ -50,6 +52,11 @@ export const UserSettingsView: React.FC<UserSettingsViewProps> = ({
   onBack,
 }) => {
   const [section, setSection] = useState<UserSettingsSection>('profile');
+  const [legal, setLegal] = useState<AuthStatus['legal']>();
+  const [showAbout, setShowAbout] = useState(false);
+  useEffect(() => {
+    api.getAuthStatus().then((st) => setLegal(st.legal)).catch(() => {});
+  }, []);
 
   // --- Custom Theme Editor State ---
   const [themeEditId, setThemeEditId] = useState<string | null>(null); // null = new theme
@@ -1227,6 +1234,14 @@ export const UserSettingsView: React.FC<UserSettingsViewProps> = ({
           )}
         </div>
       </div>
+
+      {/* Footer: legal notices of this instance and project info */}
+      <LegalLinks legal={legal} className="pt-4 border-t border-border">
+        <button type="button" onClick={() => setShowAbout(true)} className="hover:text-main underline-offset-2 hover:underline">
+          Über MindSift
+        </button>
+      </LegalLinks>
+      {showAbout && <AboutModal onClose={() => setShowAbout(false)} />}
     </div>
   );
 };