Jarvis needs a licence key, and this says what a licensed instance reports

The stack now refuses to create new organizations, users or agents without
`JARVIS_LICENSE_KEY`. Everything already set up keeps running, and an instance
with no key contacts nobody at all — but a fresh install gets as far as its
first administrator account and then needs a key, and that was documented
nowhere here.

The README now lists, in full and field by field, everything a licensed
instance sends: counts and a version string, no names, no addresses, no
conversation text, no asset inventory, no credentials. The only field that
identifies your network rather than measuring something is the public URL, and
it can be switched off.

docker-compose.yml

@@ -100,6 +100,10 @@ services:
       # log, in the session list and in the enrollment rate limit.
       TRUST_PROXY_HOPS: ${TRUST_PROXY_HOPS:-2}
 
+      # Required to create new organizations, users or agents. Without it an instance keeps running
+      # everything it already has, creates nothing new, and contacts nobody. See the README.
+      JARVIS_LICENSE_KEY: ${JARVIS_LICENSE_KEY:-}
+
       AGENT_HEARTBEAT_INTERVAL_SEC: ${AGENT_HEARTBEAT_INTERVAL_SEC:-30}
       RUN_SHUTDOWN_GRACE_SEC: ${RUN_SHUTDOWN_GRACE_SEC:-25}