feat: add Flyway migrations for users, roles, and permissions

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main/resources/db/migration/V001__create_users_table.sql

@@ -0,0 +1,12 @@
+CREATE TABLE users (
+    id          UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    email       VARCHAR(255) NOT NULL UNIQUE,
+    password    VARCHAR(255) NOT NULL,
+    name        VARCHAR(255) NOT NULL,
+    status      VARCHAR(20)  NOT NULL DEFAULT 'ACTIVE',
+    created_at  TIMESTAMPTZ  NOT NULL DEFAULT now(),
+    updated_at  TIMESTAMPTZ  NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_users_email ON users (email);
+CREATE INDEX idx_users_status ON users (status);