feat: add stress testing tool for dedicated server stability validation

Python-based bot tool that rapidly connects/disconnects to the server
using the full LCE protocol (PreLogin, Login, cipher handshake, identity
tokens, keepalive). Configurable concurrent bots, hold times, burst
joins, movement packets, and duration. Includes batch files for common
test scenarios (basic, aggressive, movement, burst, endurance).

tools/stress-test/test_basic.bat

@@ -0,0 +1,8 @@
+@echo off
+REM Basic connect/disconnect churn - 50 cycles, 8 concurrent bots
+set /p HOST="Server IP [127.0.0.1]: " || set HOST=127.0.0.1
+set /p PORT="Server Port [19132]: " || set PORT=19132
+if "%HOST%"=="" set HOST=127.0.0.1
+if "%PORT%"=="" set PORT=19132
+python "%~dp0stress_test.py" %HOST% %PORT%
+pause