Refactor project structure: replace User class with ChatUser, integrate Database class, and update CMake configuration for new files

database.cpp

@@ -0,0 +1,42 @@
+#include "database.h"
+#include <pqxx/pqxx>
+#include <stdexcept>
+
+namespace Yc {
+namespace Lib {
+
+Database::Database(std::shared_ptr<Config> config)
+{
+    // Hole Verbindungsdaten aus der Config
+    std::string dbname   = config->value("database", "database").asString();
+    std::string user     = config->value("database", "user").asString();
+    std::string password = config->value("database", "password").asString();
+    std::string host     = config->value("database", "host").asString();
+
+    std::string conninfo = 
+        "dbname=" + dbname +
+        " user=" + user +
+        " password=" + password +
+        " host=" + host;
+
+    try {
+        _connection = std::make_unique<pqxx::connection>(conninfo);
+        if (!_connection->is_open()) {
+            throw std::runtime_error("Failed to open database connection");
+        }
+    } catch (const std::exception& e) {
+        throw std::runtime_error(std::string("Database connection error: ") + e.what());
+    }
+}
+
+// Beispielmethode für eine Abfrage
+pqxx::result Database::exec(const std::string& query)
+{
+    pqxx::work txn(*_connection);
+    pqxx::result r = txn.exec(query);
+    txn.commit();
+    return r;
+}
+
+} // namespace Lib
+} // namespace Yc