InstrumentServer is a general-purpose SCPI-over-TCP server that can
host any device implementing the SCPIDevice protocol (process method).
Moving it from simulation/ to instruments/transport/ reflects this:
- simulation package now depends on instruments package
- InstrumentServer can host both virtual and real instrument adapters
- Added SCPIDevice Protocol for type-safe device registration
Test connection handling, multiple clients, instrument access across
all three virtual instruments, physics engine integration, and error
handling. Update pytest-asyncio config for v1.x compatibility.