API: ability to add (external) widgets to quote creation

Description:

Currently, the API only supports creating quotes from an existing template. There is no endpoint to create a quote directly, and templates cannot be deleted via the API either, making a clean programmatic workflow impossible today.

We would like the API to support creating quotes directly, including the ability to add widgets and populate quote content, without needing an intermediary template step. This would unlock automation workflows where quotes are generated programmatically from external systems and then refined by a human before sending.

Expected behaviour:

A single API call creates a draft quote, optionally pre-populated with widgets and/or line items, ready for review and sending.

Current workaround:

None. Template deletion is not available via the API, so the create-from-template approach is not a viable workaround.