Add LAN discovery and Local servers UI

Adds LAN server discovery and a Local tab in the multiplayer UI so clients can find relays on the same LAN. Introduces a new F4T::LanDiscovery module (plugin/include/F4TLanDiscovery.h, plugin/src/F4TLanDiscovery.cpp) that probes LAN hosts via UDP discover (port 7778) and TCP welcome fallback (port 7777). Server-side support includes a UDP responder (server/lan_discovery.py) and integration in server_core.py to start/stop discovery.

Plugin changes (F4TServerBrowserBridge/Data) add background scanning, dispatch results to the game thread, new local-server storage and events (scanLocalServers, localServersUpdated, localScanStarted/localScanFinished), and small join/recent handling updates. UI changes (ui/.../app.js and components) add localServers state, scanning UX, Recent persistence (localStorage), and join logic for local/direct entries. Docs updated (docs/protocol.md, docs/dev-log.md, server/README.md) and build script links iphlpapi. Also removes two unused exported sprite PNGs.

ui/views/CommonwealthOnline/browser/components/controller-prompts.js

@@ -51,6 +51,14 @@
         ]);
       }
 
+      if (state.activeTab === "local") {
+        return TAB_SWITCH_PROMPTS.concat([
+          { key: "A", label: "Join" },
+          { key: "X", label: "Scan" },
+          { key: "B", label: "Back" }
+        ]);
+      }
+
       if (state.focusZone === "filters") {
         var isReset = state.selectedFilterIndex === CO_Filters.FILTER_ROWS.length;
         return TAB_SWITCH_PROMPTS.concat([

ui/views/CommonwealthOnline/browser/components/server-list.js

@@ -8,28 +8,82 @@
       return "co-ping-bad";
     },
 
+    isLocalHost: function (host) {
+      if (!host) return false;
+      return /^(127\.0\.0\.1|localhost|::1)$/i.test(String(host).trim());
+    },
+
+    displayName: function (server) {
+      if (!server) return "";
+      var host = server.host || server.address || "";
+      var port = server.port > 0 ? server.port : 7777;
+      var name = String(server.name || "").trim();
+      var isLocal = server.region === "Local" || CO_ServerList.isLocalHost(host);
+      var isDirect = server.id === "direct" || name === "Direct Connect";
+      if (!name || isLocal || isDirect) {
+        return (host || "127.0.0.1") + ":" + port;
+      }
+      return name;
+    },
+
     render: function (root, state) {
       var wrap = root.querySelector(".co-server-list-wrap");
       var list = root.querySelector(".co-server-list");
       if (!wrap || !list) return;
 
       wrap.className = "co-server-list-wrap" + (state.focusZone === "server-list" ? " focused" : "");
+      var isRecent = state.activeTab === "recent";
+      var isLocal = state.activeTab === "local";
 
       if (!state.servers.length) {
-        list.innerHTML = '<div class="co-empty">No servers found</div>';
+        var emptyText = "No servers found";
+        if (isRecent) emptyText = "No recent servers";
+        else if (isLocal) {
+          emptyText = state.isScanningLocal ?
+            "Scanning local network..." :
+            "No local servers found. Check the host PC is running server.py and firewall allows UDP 7778 / TCP 7777.";
+        }
+        list.innerHTML = '<div class="co-empty">' + emptyText + "</div>";
         CO_ServerList.updateScrollIndicator(wrap, list);
         return;
       }
 
       list.innerHTML = state.servers.map(function (server, index) {
         var selected = index === state.selectedServerIndex ? " selected" : "";
+        var label = CO_ServerList.displayName(server);
+
+        if (isRecent) {
+          return (
+            '<div class="co-server-row' + selected + '" data-index="' + index + '" data-id="' + escapeAttr(server.id || "") + '">' +
+            '<div class="co-server-row-left">' +
+            '<span class="co-server-row-name">' + escapeHtml(label) + "</span>" +
+            "</div>" +
+            "</div>"
+          );
+        }
+
+        if (isLocal) {
+          var pingCls = CO_ServerList.pingClass(server.ping || 0);
+          return (
+            '<div class="co-server-row' + selected + '" data-index="' + index + '" data-id="' + escapeAttr(server.id || "") + '">' +
+            '<div class="co-server-row-left">' +
+            '<span class="co-server-row-name">' + escapeHtml(label) + "</span>" +
+            "</div>" +
+            '<div class="co-server-row-right">' +
+            "<span>" + (server.players || 0) + "/" + (server.maxPlayers || 16) + "</span>" +
+            '<span class="co-ping ' + pingCls + '">' + (server.ping || 0) + " ms</span>" +
+            "</div>" +
+            "</div>"
+          );
+        }
+
         var fav = server.favorite ? " on" : "";
         var pingCls = CO_ServerList.pingClass(server.ping);
         return (
           '<div class="co-server-row' + selected + '" data-index="' + index + '" data-id="' + escapeAttr(server.id) + '">' +
           '<div class="co-server-row-left">' +
           '<span class="co-fav' + fav + '">' + (server.favorite ? "\u2605" : "\u2606") + "</span>" +
-          '<span class="co-server-row-name">' + escapeHtml(server.name) + "</span>" +
+          '<span class="co-server-row-name">' + escapeHtml(label) + "</span>" +
           "</div>" +
           '<div class="co-server-row-right">' +
           "<span>" + server.players + "/" + server.maxPlayers + "</span>" +

ui/views/CommonwealthOnline/browser/components/tabs.js

@@ -1,7 +1,7 @@
 (function () {
   "use strict";
 
-  var TAB_ORDER = ["direct-connect", "server-browser", "favorites", "recent"];
+  var TAB_ORDER = ["direct-connect", "server-browser", "local", "favorites", "recent"];
 
   window.CO_Tabs = {
     TAB_ORDER: TAB_ORDER,
@@ -13,6 +13,7 @@
       var labels = {
         "direct-connect": "Direct Connect",
         "server-browser": "Browse",
+        local: "Local",
         favorites: "Favorites",
         recent: "Recent"
       };