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/lotus-terminal.css.ts

@@ -0,0 +1,28 @@
+import { globalStyle, style } from '@vanilla-extract/css';
+
+export const lotusTerminalBodyClass = style({});
+
+globalStyle(`body.${lotusTerminalBodyClass}`, {
+  fontFamily: "'JetBrains Mono', 'Fira Code', 'Cascadia Code', Consolas, 'Courier New', monospace",
+  letterSpacing: '0.01em',
+});
+
+globalStyle(`body.${lotusTerminalBodyClass} *`, {
+  fontFamily: "'JetBrains Mono', 'Fira Code', 'Cascadia Code', Consolas, 'Courier New', monospace !important" as any,
+});
+
+globalStyle(`body.${lotusTerminalBodyClass}::after`, {
+  content: '""',
+  position: 'fixed',
+  top: 0,
+  left: 0,
+  right: 0,
+  bottom: 0,
+  pointerEvents: 'none',
+  zIndex: 9999,
+  backgroundImage: 'repeating-linear-gradient(0deg, transparent, transparent 2px, rgba(0,0,0,0.12) 2px, rgba(0,0,0,0.12) 4px)',
+});
+
+globalStyle(`body.${lotusTerminalBodyClass} input, body.${lotusTerminalBodyClass} textarea`, {
+  caretColor: '#ff3300',
+});