perf(startup): stat dragonxd instead of reading it for the update offer

On Windows every full-node launch read the whole installed dragonxd.exe
(about 16.7 MB) on the UI thread and byte-scanned it for a version
string, to decide whether to offer the bundled node, which only needs
whether the file exists and its size. getInstalledDaemonInfo() takes a
scanVersion flag, and the update offer now only stats the file.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/resources/embedded_resources.cpp

@@ -663,7 +663,7 @@ static std::string scanBinaryVersion(const uint8_t* data, std::size_t size)
     return "";
 }
 
-DaemonBinaryInfo getInstalledDaemonInfo()
+DaemonBinaryInfo getInstalledDaemonInfo(bool scanVersion)
 {
     DaemonBinaryInfo info;
     std::string daemonDir = getDaemonDirectory();
@@ -688,6 +688,7 @@ DaemonBinaryInfo getInstalledDaemonInfo()
     }
 
     // Read the binary and scan for its version stamp (one-off; caller caches the result).
+    if (!scanVersion) return info;
     std::ifstream f(info.path, std::ios::binary);
     if (f) {
         f.seekg(0, std::ios::end);

src/resources/embedded_resources.h

@@ -48,7 +48,8 @@ struct BundledDaemonInfo {
 };
 
 // Read + scan the installed dragonxd (reads the file; call off the UI thread or cache the result).
-DaemonBinaryInfo getInstalledDaemonInfo();
+// scanVersion=false: stat only (exists / size / modifiedEpoch), no 16 MB read.
+DaemonBinaryInfo getInstalledDaemonInfo(bool scanVersion = true);
 // Info about the bundled daemon (scans the embedded bytes once, cached).
 BundledDaemonInfo getBundledDaemonInfo();
 // Force-overwrite the installed dragonx binaries (dragonxd/cli/tx) with the bundled ones. The