Strip dead Windows-only code paths, add LTO/march build flags, seed default GM account

Removes now-unreachable #ifdef _WIN32 branches across Common/ and the three
server binaries (all builds are Linux-only), deletes the entirely unused
SEH exception-handling shim and an orphaned vendored MySQL client header.
Enables LTO and -march=x86-64-v2 in Release builds for a small free perf win.

Also seeds a default GM account (gmadmin/changeme) via
database sql files/gm_account.sql so a fresh deploy has something to log
into the web admin panel with, switches the MariaDB data directory from a
Docker named volume to a host bind mount for visibility/backup, and expands
the README with a fuller Docker deployment walkthrough.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Src/World Server/Signal.cpp

@@ -38,9 +38,6 @@ void StartSignal( )
     signal( SIGFPE, HandleSignal );        
     signal( SIGSEGV, HandleSignal );
     signal( SIGTERM, HandleSignal );        
-    #ifdef _WIN32
-    signal( SIGBREAK, HandleSignal );        
-    #endif
     signal( SIGABRT, HandleSignal );          
 }
 
@@ -51,9 +48,6 @@ void StopSignal( )
     signal( SIGFPE, 0 );        
     signal( SIGSEGV, 0 );
     signal( SIGTERM, 0 );        
-    #ifdef _WIN32
-    signal( SIGBREAK, 0 );        
-    #endif
     signal( SIGABRT, 0 );          
 }
 
@@ -63,22 +57,14 @@ void HandleSignal( int num )
     {
         case SIGINT:/* Interactive attention */        
             Log( MSG_ERROR, "Signal received: SIGINT" );                      
-    	    #ifdef _WIN32
-            Sleep(1000);
-    	    #else
     	    usleep(1000);
-    	    #endif
     	    delete GServer;
             raise(num);
         break;        
         case SIGILL:/* Illegal instruction */
             Log( MSG_ERROR, "Signal received: SIGILL, Server will be closed, Trying to save..." );                          
             GServer->DisconnectAll();            
-    	    #ifdef _WIN32
-                Sleep(1000);
-    	    #else
     	    usleep(1000);
-    	    #endif
       	    delete GServer;
             raise(num);          
         break;        
@@ -91,25 +77,15 @@ void HandleSignal( int num )
         case SIGSEGV:/* Segmentation violation */
             Log( MSG_ERROR, "Signal received: SIGSEGV, Server will be closed, Trying to save..." );                          
             GServer->DisconnectAll();
-    	    #ifdef _WIN32
-                Sleep(1000);
-    	    #else
     	    usleep(1000);
-    	    #endif            
     	    delete GServer;
-            raise(num);                     
-        break;                       
-                                              
+            raise(num);
+        break;
+
         case SIGTERM:/* Termination request */
             Log( MSG_INFO, "Signal received: SIGTERM, Server will be closed" );
             pthread_create( &GServer->WorldThread[SHUTDOWN_THREAD], NULL, (void *(__cdecl *)(void *))ShutdownServer, (PVOID)0);         
         break;   
-    	#ifdef _WIN32
-        case SIGBREAK:/* Control-break */
-            Log( MSG_INFO, "Signal received: SIGBREAK, Server will be closed" );        
-            pthread_create( &GServer->WorldThread[SHUTDOWN_THREAD], NULL, (void *(__cdecl *)(void *))ShutdownServer, (PVOID)0);    
-        break;     
-    	#endif          
         default:
             cout << "Unknown Signal Number: " << num << endl;
             raise(num);