feat(ntfy): separate C&C topic from message ingestion

- Add ntfy_cc_topic config for command and control
- Add separate NtfyPoller for C&C in StreamController
- Implement serial-port-like interface: commands are executed and responses are sent back to the same topic
- Update cmdline.py to use C&C topic

cmdline.py

@@ -25,7 +25,12 @@ from engine import config
 from engine.effects.controller import handle_effects_command
 from engine.terminal import CLR, CURSOR_OFF, CURSOR_ON, G_DIM, G_HI, RST, W_GHOST
 
-TOPIC = config.NTFY_TOPIC
+try:
+    CC_TOPIC = config.NTFY_CC_TOPIC
+except AttributeError:
+    CC_TOPIC = "https://ntfy.sh/klubhaus_terminal_mainline_cc/json"
+
+TOPIC = CC_TOPIC
 
 
 def send_command(cmd: str) -> str: