⚡️(frontend) optimize participant metadata rendering on raised hand

Push state down into the participant metadata subtree so a raised
hand change no longer re-renders the whole metadata block.

Use the children-as-props pattern so only the item actually related
to the raised hand re-renders when its state changes.

This also better encapsulates the color-update logic tied to the
raised-hand state.

src/frontend/src/features/participantTile/components/ParticipantMetadata.tsx

@@ -1,7 +1,3 @@
-import {
-  useRaisedHand,
-  useRaisedHandPosition,
-} from '@/features/rooms/livekit/hooks/useRaisedHand'
 import {
   ConnectionQualityIndicator,
   LockLockedIcon,
@@ -12,8 +8,8 @@ import {
 import { HStack } from '@/styled-system/jsx'
 import { Participant } from 'livekit-client'
 import { MutedMicIndicator } from './MutedMicIndicator'
-import { RiHand } from '@remixicon/react'
 import { ParticipantName } from './ParticipantName'
+import { RaisedHandMetadataWrapper } from './RaisedHandMetadataWrapper'
 
 export const ParticipantMetadata = ({
   participant,
@@ -24,52 +20,15 @@ export const ParticipantMetadata = ({
 }) => {
   const { identity, name } = useParticipantInfo({ participant })
   const isEncrypted = useIsEncrypted(participant)
-  const { isHandRaised } = useRaisedHand({ participant })
-  const { positionInQueue, firstInQueue } = useRaisedHandPosition({
-    participant,
-  })
 
   return (
     <div className="lk-participant-metadata">
       <HStack gap={0.25}>
         {!isScreenShare && <MutedMicIndicator participant={participant} />}
-        <div
-          className="lk-participant-metadata-item"
-          style={{
-            padding: '0.1rem 0.25rem',
-            backgroundColor:
-              isHandRaised && !isScreenShare
-                ? firstInQueue
-                  ? '#fde047'
-                  : 'white'
-                : undefined,
-            color: isHandRaised && !isScreenShare ? 'black' : undefined,
-            transition: 'background 200ms ease, color 400ms ease',
-          }}
+        <RaisedHandMetadataWrapper
+          participant={participant}
+          enabled={!isScreenShare}
         >
-          {isHandRaised && !isScreenShare && (
-            <span
-              style={{
-                display: 'inline-flex',
-                alignItems: 'center',
-                gap: '0.1rem',
-              }}
-            >
-              <span>{positionInQueue}</span>
-              <RiHand
-                color="black"
-                size={16}
-                style={{
-                  marginRight: '0.4rem',
-                  marginLeft: '0.1rem',
-                  minWidth: '16px',
-                  animationDuration: '300ms',
-                  animationName: 'wave_hand',
-                  animationIterationCount: '2',
-                }}
-              />
-            </span>
-          )}
           {isScreenShare && (
             <ScreenShareIcon
               style={{
@@ -87,7 +46,7 @@ export const ParticipantMetadata = ({
               isScreenShare={isScreenShare}
             />
           </div>
-        </div>
+        </RaisedHandMetadataWrapper>
       </HStack>
       <ConnectionQualityIndicator className="lk-participant-metadata-item" />
     </div>

src/frontend/src/features/participantTile/components/RaisedHandMetadataWrapper.tsx

@@ -0,0 +1,91 @@
+import React, { ReactNode, RefObject, useEffect, useRef } from 'react'
+import {
+  useRaisedHand,
+  useRaisedHandPosition,
+} from '@/features/rooms/livekit/hooks/useRaisedHand'
+import { Participant } from 'livekit-client'
+import { RiHand } from '@remixicon/react'
+
+const PositionInQueue = React.memo(
+  ({ positionInQueue }: { positionInQueue?: number }) => {
+    if (!positionInQueue) return
+    return (
+      <span
+        style={{ display: 'inline-flex', alignItems: 'center', gap: '0.1rem' }}
+      >
+        <span>{positionInQueue}</span>
+        <RiHand
+          color="black"
+          size={16}
+          style={{
+            marginRight: '0.4rem',
+            marginLeft: '0.1rem',
+            minWidth: '16px',
+            animationDuration: '300ms',
+            animationName: 'wave_hand',
+            animationIterationCount: '2',
+          }}
+        />
+      </span>
+    )
+  }
+)
+
+PositionInQueue.displayName = 'PositionInQueue'
+
+const RaisedHandActiveItem = ({
+  participant,
+  targetRef,
+}: {
+  participant: Participant
+  targetRef: RefObject<HTMLElement | null>
+}) => {
+  const { positionInQueue, firstInQueue } = useRaisedHandPosition({
+    participant,
+  })
+  useEffect(() => {
+    const el = targetRef.current
+    if (!el) return
+
+    el.style.backgroundColor = firstInQueue ? '#fde047' : 'white'
+    el.style.color = 'black'
+
+    return () => {
+      el.style.backgroundColor = ''
+      el.style.color = ''
+    }
+  }, [targetRef, firstInQueue])
+
+  return <PositionInQueue positionInQueue={positionInQueue} />
+}
+
+export const RaisedHandMetadataWrapper = ({
+  participant,
+  enabled = true,
+  children,
+}: {
+  participant: Participant
+  enabled?: boolean
+  children: ReactNode
+}) => {
+  const ref = useRef(null)
+
+  const { isHandRaised } = useRaisedHand({ participant })
+  const showHand = isHandRaised && enabled
+
+  return (
+    <div
+      ref={ref}
+      className="lk-participant-metadata-item"
+      style={{
+        padding: '0.1rem 0.25rem',
+        transition: 'background 200ms ease',
+      }}
+    >
+      {showHand && (
+        <RaisedHandActiveItem participant={participant} targetRef={ref} />
+      )}
+      {children}
+    </div>
+  )
+}