feat: Optimizes speaker stats to skip occupants with 0 talk time.

Skips adding focus user and skips sending an empty message.
Keep sending participant info for those left the room, to keep existing behaviour.

resources/prosody-plugins/mod_speakerstats_component.lua

 local st = require "util.stanza";
 local socket = require "socket";
 local json = require "util.json";
+local um_is_admin = require "core.usermanager".is_admin;
 
 -- we use async to detect Prosody 0.10 and earlier
 local have_async = pcall(require, "util.async");
 
 log("info", "Starting speakerstats for %s", muc_component_host);
 
+local function is_admin(jid)
+    return um_is_admin(jid, module.host);
+end
+
 -- receives messages from client currently connected to the room
 -- clients indicates their own dominant speaker events
 function on_message(event)
 
 -- Create SpeakerStats object for the joined user
 function occupant_joined(event)
-    local room = event.room;
+    local occupant, room = event.occupant, event.room;
 
-    if is_healthcheck_room(room.jid) then
+    if is_healthcheck_room(room.jid) or is_admin(occupant.bare_jid) then
         return;
     end
 
                 -- skip reporting those without a nick('dominantSpeakerId')
                 -- and skip focus if sneaked into the table
                 if values.nick ~= nil and values.nick ~= 'focus' then
-                    local resultSpeakerStats = {};
-                    local totalDominantSpeakerTime
-                        = values.totalDominantSpeakerTime;
-
-                    -- before sending we need to calculate current dominant speaker
-                    -- state
-                    if values:isDominantSpeaker() then
-                        local timeElapsed = math.floor(
-                            socket.gettime()*1000 - values._dominantSpeakerStart);
-                        totalDominantSpeakerTime = totalDominantSpeakerTime
-                            + timeElapsed;
+                    local totalDominantSpeakerTime = values.totalDominantSpeakerTime;
+                    if totalDominantSpeakerTime > 0 or room:get_occupant_jid(jid) == nil then
+                        -- before sending we need to calculate current dominant speaker state
+                        if values:isDominantSpeaker() then
+                            local timeElapsed = math.floor(socket.gettime()*1000 - values._dominantSpeakerStart);
+                            totalDominantSpeakerTime = totalDominantSpeakerTime + timeElapsed;
+                        end
+
+                        users_json[values.nick] =  {
+                            displayName = values.displayName,
+                            totalDominantSpeakerTime = totalDominantSpeakerTime
+                        };
                     end
-
-                    resultSpeakerStats.displayName = values.displayName;
-                    resultSpeakerStats.totalDominantSpeakerTime
-                        = totalDominantSpeakerTime;
-                    users_json[values.nick] = resultSpeakerStats;
                 end
             end
 
+            if next(users_json) == nil then
+                return;
+            end
+
             local body_json = {};
             body_json.type = 'speakerstats';
             body_json.users = users_json;