feat: enhance billboard monitor setup with explicit configuration and auto-detection

manager/display.lua

@@ -163,9 +163,8 @@ function D.setupSmelterMonitor()
 end
 
 function D.setupBillboardMonitor()
-    if not cfg.BILLBOARD_MONITOR or cfg.BILLBOARD_MONITOR == "" then
-        return false
-    end
+    -- If explicitly configured, use that name
+    if cfg.BILLBOARD_MONITOR and cfg.BILLBOARD_MONITOR ~= "" then
         local mon = peripheral.wrap(cfg.BILLBOARD_MONITOR)
         if mon and mon.setTextScale then
             D.billboardMon = mon
@@ -174,6 +173,22 @@ function D.setupBillboardMonitor()
             return true
         end
         return false
+    end
+    -- Auto-detect: find any monitor not already used by main/smelter
+    for _, name in ipairs(peripheral.getNames()) do
+        if peripheral.getType(name) == "monitor"
+           and name ~= D.monName
+           and name ~= D.smelterMonName then
+            local mon = peripheral.wrap(name)
+            if mon and mon.setTextScale then
+                D.billboardMon = mon
+                D.billboardMonName = name
+                D.billboardMon.setTextScale(0.5)
+                return true
+            end
+        end
+    end
+    return false
 end
 
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