feat: 完善后端脚手架基础能力

migrations/postgres/20260809000100_create_users.sql

@@ -0,0 +1,7 @@
+CREATE TABLE "users" (
+  "id" bigserial,
+  "username" varchar(64) NOT NULL,
+  "password" varchar(255) NOT NULL,
+  PRIMARY KEY ("id")
+);
+CREATE UNIQUE INDEX "idx_users_username" ON "users" ("username");

migrations/postgres/atlas.sum

@@ -0,0 +1,2 @@
+h1:KL8m6Hvz0rQhkIfZfIWtoDNwAe1u9V3jCr/y1WE4rfM=
+20260809000100_create_users.sql h1:sbELXVx7emjO8qCox06MIhKn70i/adn89MUIgDTLCto=