Add API endpoint to update quote widget content (html-content blocks)

We're automating NCE renewal quotes via the public API. Our workflow creates draft quotes with templateId and products, this works great.

However, we also want to inject a dynamic HTML license overview (which users have which licenses) into an html-content widget in the quote. There's currently no API endpoint to set widget content.

Request: Either allow updating widget content on existing quotes:

PUT /quote/{id}/widget/{index}

{ "contentTemplate": "" }

Or allow widget overrides during creation:

POST /quote

{ "templateId": "...", "widgetOverrides": { "1": { "contentTemplate": "" } } }

Use case: MSP automation, generating renewal quotes with dynamic data from external systems.