Add Lotus Terminal Mode + fix all remaining Cinny branding

- New: Lotus Terminal Mode toggle in Appearance settings
  - Red phosphor color scheme (bg #0a0000, primary #ff3300, accent #00dd66)
  - Monospace font override (JetBrains Mono / Fira Code / Cascadia Code)
  - Retro CRT scanline overlay via CSS pseudo-element
  - Wired into ThemeManager with dedicated lotusTerminalBodyClass
- Branding: replace all user-visible Cinny references with Lotus Chat
  - WelcomePage, AuthLayout, SplashScreen, index.html meta tags
  - Device display names in login/register/token flows
  - System notification brand field
  - (Preserved internal Matrix protocol CinnySpaces event type)

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

src/app/pages/ThemeManager.tsx

@@ -3,11 +3,13 @@ import { configClass, varsClass } from 'folds';
 import {
   DarkTheme,
   LightTheme,
+  LotusTerminalTheme,
   ThemeContextProvider,
   ThemeKind,
   useActiveTheme,
   useSystemThemeKind,
 } from '../hooks/useTheme';
+import { lotusTerminalBodyClass } from '../../lotus-terminal.css';
 import { useSetting } from '../state/hooks/settings';
 import { settingsAtom } from '../state/settings';
 
@@ -31,19 +33,23 @@ export function UnAuthRouteThemeManager() {
 export function AuthRouteThemeManager({ children }: { children: ReactNode }) {
   const activeTheme = useActiveTheme();
   const [monochromeMode] = useSetting(settingsAtom, 'monochromeMode');
+  const [lotusTerminal] = useSetting(settingsAtom, 'lotusTerminal');
+
+  const effectiveTheme = lotusTerminal ? LotusTerminalTheme : activeTheme;
 
   useEffect(() => {
     document.body.className = '';
     document.body.classList.add(configClass, varsClass);
-
-    document.body.classList.add(...activeTheme.classNames);
-
-    if (monochromeMode) {
+    document.body.classList.add(...effectiveTheme.classNames);
+    if (lotusTerminal) {
+      document.body.classList.add(lotusTerminalBodyClass);
+    }
+    if (monochromeMode && !lotusTerminal) {
       document.body.style.filter = 'grayscale(1)';
     } else {
       document.body.style.filter = '';
     }
-  }, [activeTheme, monochromeMode]);
+  }, [effectiveTheme, monochromeMode, lotusTerminal]);
 
-  return <ThemeContextProvider value={activeTheme}>{children}</ThemeContextProvider>;
+  return <ThemeContextProvider value={effectiveTheme}>{children}</ThemeContextProvider>;
 }