Add TCP server integration tests

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.

pyproject.toml

@@ -86,5 +86,8 @@ ignore_missing_imports = true
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
-asyncio_mode = "auto"
 addopts = "-v --tb=short"
+
+[tool.pytest-asyncio]
+mode = "auto"
+default_fixture_loop_scope = "function"