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/features/settings/general/General.tsx

@@ -310,6 +310,7 @@ function Appearance() {
   const [monochromeMode, setMonochromeMode] = useSetting(settingsAtom, 'monochromeMode');
   const [twitterEmoji, setTwitterEmoji] = useSetting(settingsAtom, 'twitterEmoji');
   const [perMessageProfiles, setPerMessageProfiles] = useSetting(settingsAtom, 'perMessageProfiles');
+  const [lotusTerminal, setLotusTerminal] = useSetting(settingsAtom, 'lotusTerminal');
 
   return (
     <Box direction="Column" gap="100">
@@ -371,6 +372,13 @@ function Appearance() {
           after={<Switch variant="Primary" value={perMessageProfiles} onChange={setPerMessageProfiles} />}
         />
       </SequenceCard>
+      <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
+        <SettingTile
+          title="Lotus Terminal Mode"
+          description="Red phosphor color scheme, monospace font, and retro CRT scanlines. A full visual overhaul."
+          after={<Switch variant="Primary" value={lotusTerminal} onChange={setLotusTerminal} />}
+        />
+      </SequenceCard>
     </Box>
   );
 }

src/app/features/settings/notifications/SystemNotification.tsx

@@ -27,7 +27,7 @@ function EmailNotification() {
             device_display_name: email,
             lang: 'en',
             data: {
-              brand: 'Cinny',
+              brand: 'Lotus Chat',
             },
             append: true,
           });