feat: schéma Drizzle/SQLite (machines, snapshots, executions)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/db/migrate.ts

@@ -0,0 +1,7 @@
+// server/db/migrate.ts
+import { migrate } from "drizzle-orm/better-sqlite3/migrator";
+import { db } from "./client.js";
+
+export function runMigrations(): void {
+  migrate(db, { migrationsFolder: "./server/db/migrations" });
+}