feat: typing indicator orange dots, push-to-deafen hotkey, night light filter, message length counter

- #108: TypingIndicator reads lotusTerminal setting; applies var(--lt-accent-orange)
  to container so dots inherit via backgroundColor:currentColor
- #100: CallControls registers KeyM as push-to-deafen (e.code, e.repeat guard,
  ownerDocument.body iframe-safe editable check, [callEmbed] dep array)
- P5-5: nightLightEnabled/nightLightOpacity settings; position:fixed rgba(255,140,0)
  overlay inside JotaiProvider; Night Light tile + intensity slider (5–80%) in
  Settings → Appearance
- #101: RoomInput charCount state via Slate onChange + toPlainText; resets on
  room switch; displayed before send button when count > 0

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

src/app/features/settings/general/General.tsx

@@ -325,6 +325,8 @@ function Appearance() {
     'perMessageProfiles',
   );
   const [lotusTerminal, setLotusTerminal] = useSetting(settingsAtom, 'lotusTerminal');
+  const [nightLightEnabled, setNightLightEnabled] = useSetting(settingsAtom, 'nightLightEnabled');
+  const [nightLightOpacity, setNightLightOpacity] = useSetting(settingsAtom, 'nightLightOpacity');
 
   return (
     <Box direction="Column" gap="100">
@@ -393,6 +395,42 @@ function Appearance() {
           }
         />
       </SequenceCard>
+      <SequenceCard
+        className={SequenceCardStyle}
+        variant="SurfaceVariant"
+        direction="Column"
+        gap="200"
+      >
+        <SettingTile
+          title="Night Light"
+          description="Reduce blue light with a warm orange tint overlay."
+          after={
+            <Switch variant="Primary" value={nightLightEnabled} onChange={setNightLightEnabled} />
+          }
+        />
+        {nightLightEnabled && (
+          <Box
+            direction="Column"
+            gap="100"
+            style={{ padding: `0 ${config.space.S400} ${config.space.S300}` }}
+          >
+            <Text size="T200" style={{ opacity: 0.7 }}>
+              Intensity: {nightLightOpacity}%
+            </Text>
+            <input
+              type="range"
+              min={5}
+              max={80}
+              value={nightLightOpacity}
+              onChange={(e: React.ChangeEvent<HTMLInputElement>) =>
+                setNightLightOpacity(parseInt(e.target.value, 10))
+              }
+              style={{ width: '100%' }}
+            />
+          </Box>
+        )}
+      </SequenceCard>
+
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile
           title="Lotus Terminal Mode"