chore: add scheme for PostgreSQL

Part of #15

Author: php-coder

docker/categories.postgres.sql

@@ -0,0 +1,14 @@
+CREATE TABLE categories (
+  id bigserial NOT NULL,
+  name varchar(50) NOT NULL,
+  name_ru varchar(50) DEFAULT NULL,
+  slug varchar(50) NOT NULL,
+  created_at timestamp NOT NULL,
+  created_by bigint NOT NULL,
+  updated_at timestamp NOT NULL,
+  updated_by bigint NOT NULL,
+  PRIMARY KEY (id),
+  UNIQUE (name),
+  UNIQUE (slug),
+  UNIQUE (name_ru)
+);