compose: forward OWNER_EMAIL to the backend container

The instance-owner feature reads OWNER_EMAIL, but the backend service's
environment block is an explicit allow-list that didn't include it — so setting
it in .env never reached the app (is_instance_owner always saw "" → no owner).
Add the passthrough.

NOTE: the same allow-list omits the AI provider keys (ANTHROPIC_API_KEY,
OPENAI_*, XAI_*, OLLAMA_*) and SMTP settings, so those documented env vars also
don't currently reach the backend on this deployment. Worth a follow-up
(forward them explicitly, or switch the service to env_file) so .env actually
drives all configuration per the twelve-factor rule.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

deploy/docker-compose.yml

@@ -71,6 +71,8 @@ services:
       # alembic concurrently.
       RUN_MIGRATIONS: "1"
       DATABASE_URL: ${DATABASE_URL:-postgresql+asyncpg://provenance:provenance@postgres:5432/provenance}
+      # Instance owner/operator — the account(s) with instance-admin rights.
+      OWNER_EMAIL: ${OWNER_EMAIL:-}
       S3_ENDPOINT_URL: ${S3_ENDPOINT_URL:-http://minio:9000}
       S3_BUCKET: ${S3_BUCKET:-provenance}
       S3_ACCESS_KEY: ${S3_ACCESS_KEY:-provenance}