fix(docker): honor categorized service environment overrides (#45359)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

docker/envs/databases/db-postgres.defaults

@@ -0,0 +1,31 @@
+# Defaults for db_postgres. Copy this file to db-postgres.env to customize it.
+# Edit the settings below in the copy; docker/.env takes precedence.
+# Optional application settings are commented to retain their application defaults.
+
+PGDATA=${PGDATA:-/var/lib/postgresql/data/pgdata}
+# DB_TYPE=postgresql
+DB_USERNAME=${DB_USERNAME:-postgres}
+DB_PASSWORD=${DB_PASSWORD:-difyai123456}
+# DB_HOST=db_postgres
+# DB_PORT=5432
+DB_DATABASE=${DB_DATABASE:-dify}
+# SQLALCHEMY_POOL_SIZE=30
+# SQLALCHEMY_MAX_OVERFLOW=10
+# SQLALCHEMY_POOL_RECYCLE=3600
+# SQLALCHEMY_ECHO=false
+# SQLALCHEMY_POOL_PRE_PING=false
+# SQLALCHEMY_POOL_USE_LIFO=false
+# SQLALCHEMY_POOL_TIMEOUT=30
+# SQLALCHEMY_POOL_RESET_ON_RETURN=rollback
+POSTGRES_MAX_CONNECTIONS=${POSTGRES_MAX_CONNECTIONS:-200}
+POSTGRES_SHARED_BUFFERS=${POSTGRES_SHARED_BUFFERS:-128MB}
+POSTGRES_WORK_MEM=${POSTGRES_WORK_MEM:-4MB}
+POSTGRES_MAINTENANCE_WORK_MEM=${POSTGRES_MAINTENANCE_WORK_MEM:-64MB}
+POSTGRES_EFFECTIVE_CACHE_SIZE=${POSTGRES_EFFECTIVE_CACHE_SIZE:-4096MB}
+POSTGRES_STATEMENT_TIMEOUT=${POSTGRES_STATEMENT_TIMEOUT:-0}
+POSTGRES_IDLE_IN_TRANSACTION_SESSION_TIMEOUT=${POSTGRES_IDLE_IN_TRANSACTION_SESSION_TIMEOUT:-0}
+
+# Container variable mappings; keep these expressions unchanged in the copy.
+POSTGRES_DB=${DB_DATABASE:-dify}
+POSTGRES_PASSWORD=${DB_PASSWORD:-difyai123456}
+POSTGRES_USER=${DB_USERNAME:-postgres}