Fix build: rename GetLastError to avoid Win32 collision, fix strprintf varargs

- Rename CTorProcess::GetLastError() and CTorEmbedded::GetLastError() to
  GetStartupError() so they don't shadow the Win32 GetLastError() API,
  which caused a std::string-to-DWORD conversion error on Windows.
- Qualify the one Win32 call as ::GetLastError() for clarity.
- Pass torError.c_str() to strprintf instead of std::string, fixing
  Clang's -Wnon-pod-varargs error on macOS.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/init.cpp

@@ -1223,10 +1223,10 @@ bool AppInit2()
             fUseUPnP = false;
             #endif
         } else {
-            std::string torError = CTorEmbedded::GetInstance()->GetLastError();
+            std::string torError = CTorEmbedded::GetInstance()->GetStartupError();
             if (torError.empty())
                 torError = "No detailed Tor startup error was recorded.";
-            return InitError(strprintf(_("Tor failed to start. Triangles requires Tor to operate.\n\nDetails: %s"), torError));
+            return InitError(strprintf(_("Tor failed to start. Triangles requires Tor to operate.\n\nDetails: %s"), torError.c_str()));
         }
 
         // Initialize Tor V3 identity (Ed25519 keys, onion address)

src/tor/tor_embedded.cpp

@@ -248,7 +248,7 @@ bool CTorEmbedded::Start(int socks, int hsPort, bool enableHiddenService)
     torDataDir = (::GetDataDir() / "tor_data").string();
     running.store(StartTorProcess(torDataDir, socksPort, hiddenServicePort, hiddenServiceEnabled));
     if (!running.load()) {
-        lastError = CTorProcess::GetInstance()->GetLastError();
+        lastError = CTorProcess::GetInstance()->GetStartupError();
     }
     return running.load();
 }

src/tor/tor_embedded.h

@@ -44,8 +44,8 @@ public:
 
     // Get our .onion address (available after bootstrap)
     std::string GetOnionAddress() const { return onionHostname; }
-    std::string GetLastError() const { return lastError; }
-    void SetLastError(const std::string& value) { lastError = value; }
+    std::string GetStartupError() const { return lastError; }
+    void SetStartupError(const std::string& value) { lastError = value; }
 
     // Get the hidden service port
     int GetHiddenServicePort() const { return hiddenServicePort; }

src/tor/tor_process.cpp

@@ -314,7 +314,7 @@ bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool
             NULL, NULL,
             &si, &pi))
     {
-        DWORD err = GetLastError();
+        DWORD err = ::GetLastError();
         lastError = strprintf("CreateProcess failed for Tor binary '%s' with Windows error %lu", torBinaryPath.c_str(), err);
         printf("ERROR: Failed to start Tor process (error %lu)\n", err);
         return false;

src/tor/tor_process.h

@@ -60,7 +60,7 @@ public:
 
     // Get the Tor binary path (for diagnostics)
     std::string GetBinaryPath() const { return torBinaryPath; }
-    std::string GetLastError() const { return lastError; }
+    std::string GetStartupError() const { return lastError; }
 
     // Singleton access
     static CTorProcess* GetInstance();