Implement postgres backend and function calling

What's Changed

• Made cross-platform instructions by @lizardgai4 in #5
• Added a disclaimer by @lizardgai4 in #6
• Switched to 4o-mini by @lizardgai4 in #8
• fixed the app and removed the code related to function calling in the… by @coderkj7 in #9
• updated README file by @coderkj7 in #10
• Feature/setup postgresdb by @coderkj7 in #12

Full Changelog: 1.0.0...2.0.0