Fix: skip wasted geo-IP lookup blocking the host double-click tooltip

The online-host double-click handler called IPConverter::GetGeoLocation on
the UI thread before showing the floating tooltip, even when no local IP
database (QQWry/ip2region) was loaded. In that default configuration the
result is never displayed, yet the call issues up to three synchronous HTTP
requests (5s timeout each), delaying the tooltip by a network round trip or
worse.

Only run the lookup when a local database is actually loaded, and memoize
successful results per IP in a process-wide cache inside GetGeoLocation so
the remaining call sites (license activity, host-login fallback) do not
re-query the same IP. The cache uses function-local statics rather than
class members to keep IPConverter's layout unchanged and stay ABI-compatible
with the precompiled PrivateDesktop_Lib.lib QQWry/Ip2Region subclasses.

Co-Authored-By: deepseek-v4-pro

common/location.h

@@ -4,6 +4,8 @@
 #include <iphlpapi.h>
 #include <ws2tcpip.h>
 #include <WinInet.h>
+#include <map>
+#include <mutex>
 #include "logger.h"
 #include "jsoncpp/json.h"
 
@@ -200,6 +202,18 @@ public:
     {
         if (IP.empty()) return "";
 
+        // 进程级缓存（函数局部 static）。用局部 static 而非类成员，是为了不改动
+        // IPConverter 的类布局/尺寸——QQWry/Ip2Region 派生类来自预编译的
+        // PrivateDesktop_Lib.lib，改成员会与其产生 ABI 尺寸差异。
+        static std::map<std::string, std::string> geoCaches;
+        static std::mutex geoMutex;
+        {
+            std::lock_guard<std::mutex> lk(geoMutex);
+            auto it = geoCaches.find(IP);
+            if (it != geoCaches.end())
+                return it->second;
+        }
+
         std::string ip = IP;
         if (isLocalIP(ip)) {
             ip = getPublicIP();
@@ -249,7 +263,13 @@ public:
         InternetCloseHandle(hInternet);
 
         if (location.empty() && IsPrivateIP(ip)) {
-            return "Local Area Network";
+            location = "Local Area Network";
+        }
+
+        // 只缓存成功结果；失败不缓存，允许下次重试。
+        if (!location.empty()) {
+            std::lock_guard<std::mutex> lk(geoMutex);
+            geoCaches[IP] = location;
         }
         return location;
     }