feat(platform): screen share refresh and presence stale reaper

Add refreshScreenSharePreview for frozen stream recovery and invoke
presence.reapStalePeers during view() so ghost peers are cleared.

Co-authored-by: Cursor <[email protected]>

index.js

@@ -13728,6 +13728,22 @@ class PearcordPlatform extends EventEmitter {
     }
   }
 
+  /** Restart local share or drop stale remote preview tile (Phase 408 P408-34). */
+  async refreshScreenSharePreview (userId = null) {
+    const uid = userId || this.identity?.user?.id
+    if (!uid || !this.screenShare) return null
+    if (uid === this.identity?.user?.id && this.screenShare.active) {
+      const label = this.screenShare.label || 'Screen'
+      await this.stopScreenShare()
+      return this.startScreenShare(label)
+    }
+    if (this.screenShare.previews?.delete) {
+      this.screenShare.previews.delete(uid)
+    }
+    this.emit('screen-share')
+    return { refreshed: uid }
+  }
+
   async _firstViewableChannel (channels, preferType) {
     const list = channels || []
     if (preferType) {
@@ -22506,6 +22522,13 @@ class PearcordPlatform extends EventEmitter {
       !dismissedRekeys.has(this._dmSessionRekeyNotice.channelId)
         ? this._dmSessionRekeyNotice
         : null
+    if (this.presence?.reapStalePeers) {
+      try {
+        this.presence.reapStalePeers()
+      } catch {
+        /* presence optional during teardown */
+      }
+    }
     const activityFeed = buildActivityFeed({
       selfUserId: user?.id,
       presence: this.presence?.snapshot() || null,