feat(discourse): switch app to official discourse/discourse image (experimental)

Replaces the paywalled bitnamilegacy app with the official discourse/discourse
image behind Traefik. DB is reused as-is; uploads migrate from the legacy
bitnami volume idempotently. The wrapper entrypoint injects the db_password and
smtp_password secrets (the official image has no *_FILE support). SMTP env vars
are renamed to the official names; release notes cover the migration.

Recipe 0.8.1+3.5.0 -> 1.0.0+3.5.3 (major: new image, env/volume/port changes).

.env.sample

@@ -5,17 +5,19 @@ DOMAIN=discourse.example.com
 #EXTRA_DOMAINS=', `www.discourse.example.com`'
 LETS_ENCRYPT_ENV=production
 
-# Outgoing email
-#DISCOURSE_SMTP_HOST=
-#DISCOURSE_SMTP_PORT=
-#DISCOURSE_SMTP_USER=
-#DISCOURSE_SMTP_PROTOCOL=
-#DISCOURSE_SMTP_AUTH=
-# Set this if you send e-mails from a different domain than noreply@$DOMAIN
-#DISCOURSE_NOTIFICATION_EMAIL=$SMTP_USER
+# Admin / developer accounts (comma-separated); these become admins on signup
+DISCOURSE_DEVELOPER_EMAILS=admin@example.com
 
-# SMTP authentication
-#COMPOSE_FILE="compose.yml:compose.smtpauth.yml"
+# Outgoing email (official discourse/discourse env names)
+#DISCOURSE_SMTP_ADDRESS=
+#DISCOURSE_SMTP_PORT=587
+#DISCOURSE_SMTP_USER_NAME=
+#DISCOURSE_SMTP_AUTHENTICATION=login
+#DISCOURSE_SMTP_ENABLE_START_TLS=true
+# Set this if you send e-mail from a different address than noreply@$DOMAIN
+#DISCOURSE_NOTIFICATION_EMAIL=
+
+# SMTP password as a secret
 #SECRET_SMTP_PASSWORD_VERSION=v1
 
 SECRET_DB_PASSWORD_VERSION=v1