chore(config): production for learn.halkyon.eu, drop staging

apiServer points at learn.halkyon.eu (TLS terminated by Caddy). Production runs neither Insights nor the web server: without their blocks Serverpod doesn't start them. staging.yaml is removed; there is no staging instance.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_server/config/production.yaml

@@ -1,29 +1,20 @@
-# This is the configuration file for your production environment.
-# Typically, you will want to route the traffic through a load balancer
-# which adds SSL security through https. If you use Serverpod's standard
-# Terraform scripts to deploy your server, all you need to change in
-# this file is the examplepod.com domain name.
+# Configuration for the production instance learn.halkyon.eu.
+# Caddy terminates TLS on 443 and forwards to the API server on 8080; only the API
+# server runs in production.
 
 # Configuration for the main API server.
 apiServer:
   port: 8080
-  publicHost: api.examplepod.com
+  publicHost: learn.halkyon.eu
   publicPort: 443
   publicScheme: https
 
-# Configuration for the Insights server.
-insightsServer:
-  port: 8081
-  publicHost: insights.examplepod.com
-  publicPort: 443
-  publicScheme: https
-
-# Configuration for the web server.
-webServer:
-  port: 8082
-  publicHost: app.examplepod.com
-  publicPort: 443
-  publicScheme: https
+# No insightsServer: without this block Serverpod doesn't start Insights at all (it
+# would otherwise listen on every interface). To use Insights later, add the block
+# back (port 8081), set `serviceSecret` in the production passwords, and reach the
+# port through an SSH tunnel, never through Caddy.
+#
+# No webServer: there is no web app.
 
 # This is the database setup for your servers. The default for the Google Cloud
 # Engine Terraform configuration is to connect on a private IP address.