honcho: add honcho_deriver_autostart flag (default: false)

- New variable honcho_deriver_autostart controls service state/enabled
- honcho_deriver_enabled still controls whether Quadlet is created
- Default autostart=false after discovering deriver burns tokens autonomously
- Service is created but stopped/disabled; can be started manually if needed

ansible/roles/honcho/defaults/main.yml

@@ -92,7 +92,14 @@ honcho_dialectic_model: "claude-sonnet-4-5"
 # that means short bursts of conversation can sit unprocessed forever.
 # DERIVER_FLUSH_ENABLED=true bypasses the batching threshold so each
 # message is processed promptly.
+#
+# honcho_deriver_enabled controls whether the deriver Quadlet is created.
+# honcho_deriver_autostart controls whether the service starts on boot.
+# Set autostart=false to create the service but leave it disabled — useful
+# after discovering the deriver burns tokens autonomously despite client-side
+# cadence=0 settings.
 honcho_deriver_enabled: true
+honcho_deriver_autostart: false
 honcho_deriver_workers: 1
 honcho_deriver_polling_seconds: "1.0"
 honcho_deriver_flush_enabled: true