add database migration and UserRepository wrapper

- implemented DB migration

- added UserRepository for DB interactions

- inserted initial test record

src/db/transaction.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+class SqlliteDb;
+
+class Transaction {
+public:
+  explicit Transaction(SqlliteDb &db);
+  ~Transaction();
+
+  Transaction(const Transaction &)            = delete;
+  Transaction &operator=(const Transaction &) = delete;
+
+  Transaction(Transaction &&other) noexcept;
+  Transaction &operator=(Transaction &&other) noexcept;
+
+  void commit();
+
+private:
+  SqlliteDb *db_{ nullptr };
+  bool       isCommited_{ false };
+};