Merge the experience-gpt-api to beckn-utilities repository

## Description

Since this repository is small and is not useful as an individual project. It is better to move the repository to the beckn-utilities.
The latest code base should be moved to the [beckn-utilities](https://github.com/beckn/beckn-utilities) under the folder "gpt-api".
Once confirmed this repository can be archived/deleted.

## Goals

- [ ] Move experience-gpt-api code to beckn-utilities and archive this repository.

## Expected Outcome

- [ ] Improved code organisation
- [ ] Simplified maintenance

## Acceptance Criteria

- [ ] Successful code migration of the latest code in the mentioned repository/folder.

## Implementation Details

NA

## Mockups / Wireframes

NA

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[Please note that the below section of the ticket ****has to be in the format as mentioned as it is key to enabling proper listing of the project.**** Please only choose the options mentioned under the headings wherever applicable.]

### Product Name

experience-gpt-api

### Project Name

experience-gpt-api

### Tech Skills Needed:

Git

### Complexity

Low

### Category

Source code management

### Sub Category

Source code management

Review the latest code in the beckn/experience-gpt-api repository and the target beckn/beckn-utilities repository. Confirm the code can be migrated under the gpt-api folder, then verify the migrated contents and archive this repository once the destination is confirmed.

Written by the indexing model from the issue text.