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/room/RoomInput.tsx

@@ -150,6 +150,9 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
     const powerLevels = usePowerLevelsContext();
     const creators = useRoomCreators(room);
 
+    const [charCount, setCharCount] = useState(0);
+    useEffect(() => { setCharCount(0); }, [roomId]);
+
     const alive = useAlive();
     const [msgDraft, setMsgDraft] = useAtom(roomIdToMsgDraftAtomFamily(roomId));
     const [replyDraft, setReplyDraft] = useAtom(roomIdToReplyDraftAtomFamily(roomId));
@@ -718,6 +721,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
           onKeyDown={handleKeyDown}
           onKeyUp={handleKeyUp}
           onPaste={handlePaste}
+          onChange={(value) => setCharCount(toPlainText(value, isMarkdown).trim().length)}
           top={
             replyDraft && (
               <div>
@@ -953,6 +957,22 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
                   setTimeout(() => setLocationError(null), 4000);
                 }}
               />
+              {charCount > 0 && (
+                <Text
+                  size="T200"
+                  style={{
+                    color: 'var(--tc-surface-low)',
+                    padding: '0 4px',
+                    alignSelf: 'center',
+                    userSelect: 'none',
+                    minWidth: '2rem',
+                    textAlign: 'right',
+                    opacity: 0.7,
+                  }}
+                >
+                  {charCount}
+                </Text>
+              )}
               <IconButton
                 onClick={submit}
                 variant="SurfaceVariant"