Add mount system and crash mouse-release handler

Render mount M2 model under player with seated animation, apply creature
skin textures, server-driven speed via SMSG_FORCE_RUN_SPEED_CHANGE, and
/dismount command. X11 XUngrabPointer on crash/hang to always release mouse.

src/main.cpp

@@ -1,8 +1,33 @@
 #include "core/application.hpp"
 #include "core/logger.hpp"
 #include <exception>
+#include <csignal>
+#include <SDL2/SDL.h>
+#include <X11/Xlib.h>
+
+static void releaseMouseGrab() {
+    // Bypass SDL — talk to X11 directly (signal-safe enough for our purposes)
+    Display* dpy = XOpenDisplay(nullptr);
+    if (dpy) {
+        XUngrabPointer(dpy, CurrentTime);
+        XUngrabKeyboard(dpy, CurrentTime);
+        XFlush(dpy);
+        XCloseDisplay(dpy);
+    }
+}
+
+static void crashHandler(int sig) {
+    releaseMouseGrab();
+    std::signal(sig, SIG_DFL);
+    std::raise(sig);
+}
 
 int main([[maybe_unused]] int argc, [[maybe_unused]] char* argv[]) {
+    std::signal(SIGSEGV, crashHandler);
+    std::signal(SIGABRT, crashHandler);
+    std::signal(SIGFPE,  crashHandler);
+    std::signal(SIGTERM, crashHandler);
+    std::signal(SIGINT,  crashHandler);
     try {
         wowee::core::Logger::getInstance().setLogLevel(wowee::core::LogLevel::DEBUG);
         LOG_INFO("=== Wowee Native Client ===");
@@ -22,10 +47,12 @@ int main([[maybe_unused]] int argc, [[maybe_unused]] char* argv[]) {
         return 0;
     }
     catch (const std::exception& e) {
+        releaseMouseGrab();
         LOG_FATAL("Unhandled exception: ", e.what());
         return 1;
     }
     catch (...) {
+        releaseMouseGrab();
         LOG_FATAL("Unknown exception occurred");
         return 1;
     }