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/test-utils/render.tsx

@@ -0,0 +1,11 @@
+import { render as testingLibraryRender } from '@testing-library/react';
+import { MantineProvider } from '@mantine/core';
+import { theme } from '../src/theme';
+
+export function render(ui: React.ReactNode) {
+  return testingLibraryRender(ui, {
+    wrapper: ({ children }: { children: React.ReactNode }) => (
+      <MantineProvider theme={theme}>{children}</MantineProvider>
+    ),
+  });
+}