feat(api): add auth HTTP controller with tests

backend/src/app_state.cc

@@ -10,7 +10,11 @@ AppState& AppState::Instance() {
 }
 
 void AppState::Init(const std::string& sqlite_path) {
-  db_ = std::make_unique<db::SqliteDb>(db::SqliteDb::OpenFile(sqlite_path));
+  if (sqlite_path == ":memory:") {
+    db_ = std::make_unique<db::SqliteDb>(db::SqliteDb::OpenMemory());
+  } else {
+    db_ = std::make_unique<db::SqliteDb>(db::SqliteDb::OpenFile(sqlite_path));
+  }
   csp::db::ApplyMigrations(*db_);
 }