Add migration feature

migrations/000001.php

@@ -0,0 +1,8 @@
+<?php
+
+/** @noinspection PhpUndefinedVariableInspection */
+$db->exec('CREATE TABLE IF NOT EXISTS migrations (
+    id INTEGER PRIMARY KEY,
+    migration TEXT NOT NULL,
+    migrated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+)');