Hide inactive monsters from player display view

Inactive monsters are now filtered out of the DisplayView so DMs can
pre-stage summoned/reserve monsters without spoiling them for players.
Inactive characters remain visible since their inactive state is
player-relevant.

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

src/App.js

@@ -2414,8 +2414,9 @@ function DisplayView() {
 
   let participantsToRender = [];
   if (participants) {
-    // Show all participants, including dead ones (HP = 0)
-    participantsToRender = sortParticipantsByInitiative(participants, participants);
+    // Hide inactive monsters (pre-staged/summoned reserves) from the player view
+    const visibleParticipants = participants.filter(p => p.isActive || p.type !== 'monster');
+    participantsToRender = sortParticipantsByInitiative(visibleParticipants, visibleParticipants);
   }
 
   const displayStyles = campaignBackgroundUrl