Discourse: move from Bitnami chart to launcher-built image

The Bitnami chart and images stop at 3.5.0. Run Discourse 2026.10.0 from
an image built with the official launcher, on PostgreSQL 18, reusing the
existing uploads volume, Redis and secrets.

Update the Dex sign-in step for the new image paths, drop the removed
LDAP setting, and keep chat off now that it is bundled in core. The image
adds a real-IP rule so visitors are not all rate limited as the ingress.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

files/discourse/web_only.yml

@@ -0,0 +1,36 @@
+# Build-only config for the eom.dev Discourse image. No secrets belong here:
+# database, Redis and SMTP credentials are supplied at runtime by Kubernetes.
+templates:
+  - "templates/web.template.yml"
+  - "templates/web.ratelimited.template.yml"
+
+params:
+  version: v2026.10.0
+
+env:
+  LC_ALL: en_US.UTF-8
+  LANG: en_US.UTF-8
+  LANGUAGE: en_US.UTF-8
+  DISCOURSE_HOSTNAME: discourse.eom.dev
+  DISABLE_LETSENCRYPT: 1
+
+# Everything else the forum uses (openid-connect, reactions, math, post-voting,
+# adplugin, subscriptions, chat) is bundled in core at this version.
+hooks:
+  after_code:
+    - exec:
+        cd: $home/plugins
+        cmd:
+          - git clone https://github.com/discourse/discourse-activity-pub.git
+          - git clone https://github.com/discourse/discourse-prometheus.git
+
+run:
+  # ingress-nginx terminates TLS, so trust its X-Forwarded-For only from the pod
+  # network. Without this every visitor shares the ingress IP and hits rate limits.
+  - file:
+      path: /etc/nginx/conf.d/outlets/server/real-ip.conf
+      chmod: 644
+      contents: |
+        set_real_ip_from 10.244.0.0/16;
+        real_ip_header X-Forwarded-For;
+        real_ip_recursive on;