fix(infra): set OTEL_EXPORTER_OTLP_ENDPOINT in docker-compose.prod.yml

The endpoint belongs in the compose file (hardcoded to the in-network
Tempo service) rather than per-environment workflow files. This covers
both staging (nightly.yml) and production (release.yml) with a single
change and removes the duplicate from the nightly env-file block.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/nightly.yml

@@ -85,7 +85,6 @@ jobs:
           GLITCHTIP_SECRET_KEY=${{ secrets.GLITCHTIP_SECRET_KEY }}
           GLITCHTIP_DOMAIN=https://glitchtip.archiv.raddatz.cloud
           SENTRY_DSN=${{ secrets.SENTRY_DSN }}
-          OTEL_EXPORTER_OTLP_ENDPOINT=http://tempo:4317
           EOF
 
       - name: Verify backend /import:ro mount is wired

docker-compose.prod.yml

@@ -213,6 +213,7 @@ services:
       APP_MAIL_FROM: ${APP_MAIL_FROM:-noreply@raddatz.cloud}
       SPRING_MAIL_PROPERTIES_MAIL_SMTP_AUTH: ${MAIL_SMTP_AUTH:-true}
       SPRING_MAIL_PROPERTIES_MAIL_SMTP_STARTTLS_ENABLE: ${MAIL_STARTTLS_ENABLE:-true}
+      OTEL_EXPORTER_OTLP_ENDPOINT: http://tempo:4317
     networks:
       - archiv-net
     healthcheck: