fix(postgres): remove memory limit and add document database

Postgres was OOMKilled repeatedly with the 600Mi limit given
shared_buffers=384MB + max_connections=300. Drop the limit entirely
for the local dev cluster (keep the 400Mi request for scheduling).

Also seed a 'document' database in initdb.sh.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

k8s/infra/postgres.yaml

@@ -23,6 +23,7 @@ data:
     	CREATE DATABASE authz WITH OWNER postgres ENCODING utf8;
     	CREATE DATABASE company WITH OWNER postgres ENCODING utf8;
     	CREATE DATABASE consumer WITH OWNER postgres ENCODING utf8;
+    	CREATE DATABASE document WITH OWNER postgres ENCODING utf8;
     	CREATE DATABASE employee WITH OWNER postgres ENCODING utf8;
     	CREATE DATABASE invoice WITH OWNER postgres ENCODING utf8;
     	CREATE DATABASE notification WITH OWNER postgres ENCODING utf8;
@@ -62,8 +63,6 @@ spec:
         resources:
           requests:
             memory: 400Mi
-          limits:
-            memory: 600Mi
         ports:
         - containerPort: 5432
         env: