refactor: make Marmot group members list reactive

Expose the member list as MutableStateFlow<List<GroupMemberInfo>> on
MarmotGroupChatroom, populated by MarmotManager.syncMetadataTo alongside
the existing memberCount. MarmotGroupInfoScreen and RemoveMemberScreen
now observe it via collectAsStateWithLifecycle, so both remote commits
(already routed through syncMetadataTo in DecryptAndIndexProcessor) and
local mutations refresh the UI without manual re-queries.

Account.addMarmotGroupMember and removeMarmotGroupMember now call
syncMetadataTo right after the MLS state is mutated, mirroring the
pattern already used by updateMarmotGroupMetadata, so the local change
is visible immediately without waiting for the relay round-trip.

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/marmot/MarmotManager.kt

@@ -437,7 +437,9 @@ class MarmotManager(
             chatroom.adminPubkeys.value = metadata.adminPubkeys
             chatroom.relays.value = metadata.relays
         }
-        chatroom.memberCount.value = memberCount(nostrGroupId)
+        val members = memberPubkeys(nostrGroupId)
+        chatroom.members.value = members
+        chatroom.memberCount.value = members.size
     }
 }
 

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/marmotGroups/MarmotGroupChatroom.kt

@@ -21,6 +21,7 @@
 package com.vitorpamplona.amethyst.commons.model.marmotGroups
 
 import androidx.compose.runtime.Stable
+import com.vitorpamplona.amethyst.commons.marmot.GroupMemberInfo
 import com.vitorpamplona.amethyst.commons.model.Channel.Companion.DefaultFeedOrder
 import com.vitorpamplona.amethyst.commons.model.ListChange
 import com.vitorpamplona.amethyst.commons.model.Note
@@ -46,6 +47,7 @@ class MarmotGroupChatroom(
     var adminPubkeys = MutableStateFlow<List<HexKey>>(emptyList())
     var relays = MutableStateFlow<List<String>>(emptyList())
     var memberCount = MutableStateFlow(0)
+    var members = MutableStateFlow<List<GroupMemberInfo>>(emptyList())
     var newestMessage: Note? = null
     val unreadCount = MutableStateFlow(0)