Slim the adapter down to platform work

AsyncSingletonSlot, _websocket_url, connect_too_long and the manual
setup-wizard code go away — the client is a plain cached attribute
again and configuration comes from ChattoConfiguration. Module-level
helpers are renamed to the hermes_*_fn convention
(hermes_standalone_sender_fn et al.) so the gateway can find them, and
set_presence takes a PresenceStatus instead of a string.

test_adapter.py

@@ -25,6 +25,8 @@ import pytest_asyncio
 # Import chattolib types for tests - using vendored chattolib from adapter
 
 # -- Path setup --
+PLUGIN_ROOT = os.path.abspath(os.path.dirname(__file__))
+sys.path.insert(0, PLUGIN_ROOT)
 sys.path.insert(0, "/opt/hermes")
 sys.path.insert(0, "/root/.hermes/plugins/platforms/chatto")
 
@@ -37,7 +39,6 @@ from adapter import (
     validate_config,
     register,
 )
-
 from gateway.config import PlatformConfig
 from gateway.platforms.base import SendResult, MessageEvent, MessageType