chore(infra)!: replace CouchDB with DocumentDB in docker-compose

[ogruene]

Replace CouchDB with DocumentDB

Migrates the local development database from CouchDB to DocumentDB Local, a MongoDB-compatible document database built on PostgreSQL.

What changed

• docker-compose.yml: replaced couchdb image with ghcr.io/documentdb/documentdb/documentdb-local:latest on port 10260, updated server environment to use DATABASE_TYPE=MongoDB, new credentials, and DATABASE_SKIP_VERIFY=true for the auto-generated TLS certificate
• Renamed volume couchdb_data → documentdb_data

Why pg_isready instead of mongosh for the healthcheck

DocumentDB Local runs a MongoDB-compatible gateway (port 10260) on top of PostgreSQL (port 9712). The obvious healthcheck would use mongosh to ping the gateway — but this causes significant log pollution:

• The gateway enforces TLS using a self-signed auto-generated certificate, so mongosh requires ?tls=true&tlsAllowInvalidCertificates=true
• Every mongosh connection unconditionally issues atlasVersion and getParameter startup probes that DocumentDB does not implement, logging server-side errors on every healthcheck interval — not suppressible

pg_isready checks the underlying PostgreSQL socket directly, generates zero log entries, and is already present in the container image. The trade-off is that it does not verify the gateway layer. For local development this is acceptable since the gateway rarely fails independently of PostgreSQL.

⚠️ BREAKING CHANGE: Data from former docker-compose runs will not be available any longer.