feat: take_powerup VFX, rank fix, admin chat management

- Wire take_powerup AnimatedSprite3D on powerup pickup via add_powerup_from_item()
- Make take_powerup animation one-shot (loop: false)
- Fix rank Position label hidden at game start (visible = false, only shows when score > 0)
- Competition ranking for tied scores in main.gd
- Lobby Chat admin tab: system prefix, max messages, wipe, purge old, save config
- Chat Storage admin tab: list/browse/delete individual channel messages
- Backend RPCs: admin_get_chat_config, admin_set_chat_config, admin_purge_old_messages,
  admin_list_channel_messages, admin_delete_channel_message
- Chat config applied on lobby join (max_messages, prefix injection)

server/nakama/lua/admin.lua

@@ -336,6 +336,157 @@ function admin.rpc_admin_get_player_list(context, payload)
     return nk.json_encode({ players = players })
 end
 
+-- =============================================================================
+-- Lobby Chat Management
+-- =============================================================================
+
+function admin.rpc_admin_get_chat_config(context, payload)
+    utils.require_admin(context)
+    local configObjs = nk.storage_read({{
+        collection = "config",
+        key = "lobby_chat",
+        user_id = utils.SYSTEM_USER_ID
+    }})
+    local config = { prefix = "", max_messages = 50, max_age_days = 0 }
+    if configObjs and #configObjs > 0 and configObjs[1].value then
+        local val = configObjs[1].value
+        config.prefix = val.prefix or ""
+        config.max_messages = val.max_messages or 50
+        config.max_age_days = val.max_age_days or 0
+    end
+    return nk.json_encode({ config = config })
+end
+
+function admin.rpc_admin_set_chat_config(context, payload)
+    utils.require_admin(context)
+    local request = nk.json_decode(payload or "{}")
+    local config = {
+        prefix = request.prefix or "",
+        max_messages = request.max_messages or 50,
+        max_age_days = request.max_age_days or 0
+    }
+    nk.storage_write({{
+        collection = "config",
+        key = "lobby_chat",
+        user_id = utils.SYSTEM_USER_ID,
+        value = config,
+        permission_read = 2,
+        permission_write = 0
+    }})
+    nk.logger_info("[AdminChat] Chat config updated by " .. context.user_id)
+    return nk.json_encode({ success = true })
+end
+
+function admin.rpc_admin_purge_old_messages(context, payload)
+    utils.require_admin(context)
+    local request = nk.json_decode(payload or "{}")
+    local channelId = request.channel_id or ""
+    local maxAgeDays = request.max_age_days or 0
+
+    if channelId == "" then
+        error("channel_id is required")
+    end
+    if maxAgeDays <= 0 then
+        error("max_age_days must be > 0")
+    end
+
+    local cutoff = os.time() - (maxAgeDays * 86400)
+    local deleted = 0
+    local cursor = ""
+
+    repeat
+        local status, result = pcall(nk.channel_messages_list, channelId, 100, false, cursor)
+        if not status then break end
+
+        local messages = result.messages or {}
+        for _, msg in ipairs(messages) do
+            -- Parse create_time to compare against cutoff
+            local msgTime = 0
+            if msg.create_time then
+                -- Try ISO format: "2024-01-15T10:30:00Z"
+                local y, m, d, hh, mm, ss = msg.create_time:match("(%d+)%-(%d+)%-(%d+)T(%d+):(%d+):(%d+)")
+                if y then
+                    msgTime = os.time({
+                        year = tonumber(y), month = tonumber(m), day = tonumber(d),
+                        hour = tonumber(hh), min = tonumber(mm), sec = tonumber(ss)
+                    })
+                else
+                    -- Try unix timestamp string
+                    msgTime = tonumber(msg.create_time) or 0
+                end
+            end
+
+            if msgTime > 0 and msgTime < cutoff then
+                pcall(nk.channel_message_remove, channelId, msg.message_id)
+                deleted = deleted + 1
+            end
+        end
+
+        cursor = result.next_cursor or ""
+    until cursor == ""
+
+    nk.logger_info("[AdminChat] Purged " .. deleted .. " messages older than " .. maxAgeDays .. " days by " .. context.user_id)
+    return nk.json_encode({ success = true, deleted = deleted })
+end
+
+function admin.rpc_admin_list_channel_messages(context, payload)
+    utils.require_admin(context)
+    local request = nk.json_decode(payload or "{}")
+    local channelId = request.channel_id or ""
+    local limit = request.limit or 50
+    local cursor = request.cursor or ""
+    local forward = request.forward == nil and true or request.forward
+
+    if channelId == "" then
+        error("channel_id is required")
+    end
+
+    local status, result = pcall(nk.channel_messages_list, channelId, limit, forward, cursor)
+    if not status then
+        error("Failed to list messages: " .. tostring(result))
+    end
+
+    local msgs = {}
+    if result and result.messages then
+        for _, msg in ipairs(result.messages) do
+            table.insert(msgs, {
+                message_id = msg.message_id,
+                sender_id = msg.sender_id,
+                username = msg.username,
+                content = msg.content,
+                create_time = msg.create_time,
+                update_time = msg.update_time,
+                channel_id = msg.channel_id
+            })
+        end
+    end
+
+    return nk.json_encode({
+        messages = msgs,
+        next_cursor = result.next_cursor or "",
+        cache_cursor = result.cache_cursor or ""
+    })
+end
+
+function admin.rpc_admin_delete_channel_message(context, payload)
+    utils.require_admin(context)
+    local request = nk.json_decode(payload or "{}")
+    local channelId = request.channel_id or ""
+    local messageId = request.message_id or ""
+
+    if channelId == "" or messageId == "" then
+        error("channel_id and message_id are required")
+    end
+
+    local status, err = pcall(nk.channel_message_remove, channelId, messageId)
+    if not status then
+        error("Failed to delete message: " .. tostring(err))
+    end
+
+    nk.logger_info("[AdminChat] Deleted message " .. messageId .. " from channel " .. channelId .. " by " .. context.user_id)
+    return nk.json_encode({ success = true })
+end
+
 -- Register RPCs
 nk.register_rpc(admin.rpc_admin_kick_player, "admin_kick_player")
 nk.register_rpc(admin.rpc_admin_ban_player, "admin_ban_player")
@@ -349,6 +500,11 @@ nk.register_rpc(admin.rpc_admin_topup_gold, "admin_topup_gold")
 nk.register_rpc(admin.rpc_admin_clear_global_chat, "admin_clear_global_chat")
 nk.register_rpc(admin.rpc_admin_list_users, "admin_list_users")
 nk.register_rpc(admin.rpc_admin_delete_users, "admin_delete_users")
+nk.register_rpc(admin.rpc_admin_get_chat_config, "admin_get_chat_config")
+nk.register_rpc(admin.rpc_admin_set_chat_config, "admin_set_chat_config")
+nk.register_rpc(admin.rpc_admin_purge_old_messages, "admin_purge_old_messages")
+nk.register_rpc(admin.rpc_admin_list_channel_messages, "admin_list_channel_messages")
+nk.register_rpc(admin.rpc_admin_delete_channel_message, "admin_delete_channel_message")
 
 nk.logger_info("LUA TEST: admin module loaded successfully")
 

server/nakama/lua/utils.lua

@@ -3,6 +3,7 @@ local nk = require("nakama")
 local utils = {}
 
 utils.ADMIN_ROLES = { ["admin"] = true, ["moderator"] = true, ["owner"] = true }
+utils.SYSTEM_USER_ID = "00000000-0000-0000-0000-000000000000"
 
 function utils.is_admin(context)
     if not context.user_id then return false end