fix(ui): restore blink and live-label feedback in message control

The blink modifier in the timer preview referenced a CSS module class that
does not exist, so `style.blink` resolved to undefined and the preview never
blinked. `.blink` is a global animation class, matching how the timer view
applies it.

The "message is live" label highlight used `??` where `&&` was meant: since
`visible` is always a boolean, the active style was unreachable.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011CHxSQ6nWHuyar8feieRra

apps/client/src/features/control/message/InputRow.tsx

@@ -43,7 +43,7 @@ export default function InputRow(props: PropsWithChildren<InputRowProps>) {
 
   return (
     <div>
-      <label className={cx([style.label, visible ?? style.active])} htmlFor={label}>
+      <label className={cx([style.label, visible && style.active])} htmlFor={label}>
         {label}
       </label>
       <div className={style.inputItems}>

apps/client/src/features/control/message/TimerPreview.tsx

@@ -49,7 +49,7 @@ export default function TimerPreview() {
   })();
 
   const showColourOverride = main == 'Timer';
-  const contentClasses = cx([blink && style.blink, blackout && style.blackout]);
+  const contentClasses = cx([blink && 'blink', blackout && style.blackout]);
 
   return (
     <div className={style.preview}>