feat(01-02): create Flyway migrator service and initial migration

- Add Migrator trait with migrate/status ZIO effects
- Create V1 migration for summer_users table
- Configure Flyway with summer_migrations table and classpath location
- Migrations run manually via CLI, not on startup

summercms/resources/db/migration/V1__create_summer_users.sql

@@ -0,0 +1,26 @@
+-- Summer CMS initial schema
+-- Creates the base users table for future auth
+
+CREATE TABLE summer_users (
+    id BIGSERIAL PRIMARY KEY,
+    email VARCHAR(255) NOT NULL UNIQUE,
+    password_hash VARCHAR(255) NOT NULL,
+    created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX idx_summer_users_email ON summer_users(email);
+
+-- Trigger for updated_at
+CREATE OR REPLACE FUNCTION update_updated_at_column()
+RETURNS TRIGGER AS $$
+BEGIN
+    NEW.updated_at = NOW();
+    RETURN NEW;
+END;
+$$ language 'plpgsql';
+
+CREATE TRIGGER update_summer_users_updated_at
+    BEFORE UPDATE ON summer_users
+    FOR EACH ROW
+    EXECUTE FUNCTION update_updated_at_column();

summercms/src/db/Migrator.scala

@@ -0,0 +1,80 @@
+package db
+
+import org.flywaydb.core.Flyway
+import org.flywaydb.core.api.MigrationInfo
+import zio.*
+import javax.sql.DataSource
+
+/** Migration status summary
+  *
+  * @param current
+  *   The currently applied migration version (None if no migrations applied)
+  * @param pending
+  *   Number of pending migrations waiting to be applied
+  */
+case class MigrationStatus(current: Option[String], pending: Int)
+
+/** Flyway database migration service
+  *
+  * Wraps Flyway migrations in ZIO effects for controlled execution. Migrations are NOT auto-run on
+  * application startup - they must be explicitly invoked via CLI (Phase 5: CLI Scaffolding).
+  *
+  * Migration files are stored in: resources/db/migration/ Following Flyway naming convention:
+  * V{version}__{description}.sql
+  *
+  * Example: V1__create_summer_users.sql
+  */
+trait Migrator {
+
+  /** Run all pending migrations
+    *
+    * @return
+    *   Number of migrations applied
+    */
+  def migrate: Task[Int]
+
+  /** Get current migration status
+    *
+    * @return
+    *   Status with current version and pending count
+    */
+  def status: Task[MigrationStatus]
+}
+
+object Migrator {
+
+  /** Live implementation of Migrator backed by Flyway */
+  val live: ZLayer[DataSource, Nothing, Migrator] =
+    ZLayer.fromFunction { (ds: DataSource) =>
+      new Migrator {
+        private def flyway: Flyway =
+          Flyway.configure()
+            .dataSource(ds)
+            .locations("classpath:db/migration")
+            .table("summer_migrations")
+            .baselineOnMigrate(true)
+            .load()
+
+        override def migrate: Task[Int] =
+          ZIO.attempt {
+            flyway.migrate().migrationsExecuted
+          }
+
+        override def status: Task[MigrationStatus] =
+          ZIO.attempt {
+            val info    = flyway.info()
+            val current = Option(info.current()).map(_.getVersion.getVersion)
+            val pending = info.pending().length
+            MigrationStatus(current, pending)
+          }
+      }
+    }
+
+  /** Accessor for migrate effect */
+  def migrate: ZIO[Migrator, Throwable, Int] =
+    ZIO.serviceWithZIO[Migrator](_.migrate)
+
+  /** Accessor for status effect */
+  def status: ZIO[Migrator, Throwable, MigrationStatus] =
+    ZIO.serviceWithZIO[Migrator](_.status)
+}