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/MainProcess.cpp

@@ -356,11 +356,7 @@ PVOID MapProcess( PVOID TS )
         }
         pthread_mutex_unlock( &GServer->MapMutex );
         pthread_mutex_unlock( &GServer->PlayerMutex );
-        #ifdef _WIN32
-        Sleep(GServer->Config.MapDelay);
-        #else
         usleep(GServer->Config.MapDelay * 1000); // MapDelay is in milliseconds; usleep wants microseconds
-        #endif
     }
     pthread_exit( NULL );
 	return 0;
@@ -390,11 +386,7 @@ PVOID VisibilityProcess(PVOID TS)
         }
         pthread_mutex_unlock( &GServer->MapMutex );
         pthread_mutex_unlock( &GServer->PlayerMutex );
-        #ifdef _WIN32
-        Sleep(GServer->Config.VisualDelay);
-        #else
         usleep(GServer->Config.VisualDelay * 1000); // VisualDelay is in milliseconds; usleep wants microseconds
-        #endif
     }
     pthread_exit(NULL);
 	return 0;
@@ -429,11 +421,7 @@ PVOID WorldProcess( PVOID TS )
         }
         pthread_mutex_unlock( &GServer->MapMutex );
         GServer->RefreshFairy( );
-        #ifdef _WIN32
-        Sleep(GServer->Config.WorldDelay);
-        #else
         usleep(GServer->Config.WorldDelay * 1000); // WorldDelay is in milliseconds; usleep wants microseconds
-        #endif
     }
     pthread_exit(NULL);
 	return 0;
@@ -443,11 +431,7 @@ PVOID WorldProcess( PVOID TS )
 void ShutdownServer(PVOID TS)
 {
     int minutes = (int)(intptr_t)TS;
-    #ifdef _WIN32
-    Sleep(minutes*60000);
-    #else
     sleep(minutes*60); // minutes*60000 was milliseconds; sleep() wants seconds
-    #endif
     Log( MSG_INFO, "Saving User Information... " );
     GServer->DisconnectAll();
     Log( MSG_INFO, "Waiting Process to ShutDown... " );