Add simulation server entry point

Create SimulationServer that wires physics engine to all virtual
instruments and exposes them over TCP. Add 'serve' CLI command to
start the server with configurable ports and physics rate.

src/py_dvt_ate/simulation/__init__.py

@@ -4,6 +4,7 @@ Provides virtual instruments backed by a coupled thermal-electrical
 physics engine. Used for development and testing without real hardware.
 """
 
+from py_dvt_ate.simulation.server import ServerConfig, SimulationServer
 from py_dvt_ate.simulation.tcp_server import InstrumentServer
 
-__all__ = ["InstrumentServer"]
+__all__ = ["InstrumentServer", "ServerConfig", "SimulationServer"]