feat(cmdline): use C&C topic with response polling

- Rewrite cmdline to send commands via ntfy and wait for response
- Add NtfyResponsePoller class for serial-port-like interface
- Add integration tests for ntfy topics (test read/write)
- Add NTFY_CC_TOPIC export to config

engine/config.py

@@ -195,6 +195,7 @@ FIREHOSE = "--firehose" in sys.argv
 
 # ─── NTFY MESSAGE QUEUE ──────────────────────────────────
 NTFY_TOPIC = "https://ntfy.sh/klubhaus_terminal_mainline/json"
+NTFY_CC_TOPIC = "https://ntfy.sh/klubhaus_terminal_mainline_cc/json"
 NTFY_RECONNECT_DELAY = 5  # seconds before reconnecting after a dropped stream
 MESSAGE_DISPLAY_SECS = 30  # how long a message holds the screen