This commit improves the Swagger documentation by using rswag to generate it from the request specs.
The following changes were made:
- All request specs in `spec/requests/api/v1/` were updated to use the rswag DSL.
- The `spec/swagger_helper.rb` was configured to generate a `swagger.json` file.
- The `config/database.yml` was updated to use environment variables, which makes it easier to use in different environments.
- The generated `swagger.json` file is now based on the OpenAPI 3.0 specification.