Add OpenAI and PostgreSQL credential management

- Implemented OpenAICredencial class for managing OpenAI API keys.
- Created OpenAICredencialModel and OpenAICredencialMapper for SQLAlchemy integration.
- Developed OpenAICredencialRepo for CRUD operations on OpenAI credentials.
- Established OpenAICliente class for interacting with OpenAI API.
- Introduced PostgresCredencial class for managing PostgreSQL connection details.
- Created PostgresCredencialModel and PostgresCredencialMapper for SQLAlchemy integration.
- Developed PostgresCredencialRepo for CRUD operations on PostgreSQL credentials.
- Added base connection class and PostgreSQL connection implementation.
- Included environment variable loading for sensitive data management.

frontend/src/pages/Home.page.tsx

@@ -0,0 +1,11 @@
+import { ColorSchemeToggle } from '../components/ColorSchemeToggle/ColorSchemeToggle';
+import { Welcome } from '../components/Welcome/Welcome';
+
+export function HomePage() {
+  return (
+    <>
+      <Welcome />
+      <ColorSchemeToggle />
+    </>
+  );
+}