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/App.tsx

@@ -0,0 +1,13 @@
+import '@mantine/core/styles.css';
+
+import { MantineProvider } from '@mantine/core';
+import { Router } from './Router';
+import { theme } from './theme';
+
+export default function App() {
+  return (
+    <MantineProvider theme={theme}>
+      <Router />
+    </MantineProvider>
+  );
+}