🚀 Feature: JSON output option

The user may want to parse the output manually in a different action step.

An option, for example, `output_type: "json"` could be useful to allow such customization more easily.

A format such as the following may be useful (all the params, plus the svg card url)

```jsonc
[
{
"id": "...",
"title": "...",
"timestamp": "...",
"background_color": "...",
"title_color": "...",
"stats_color": "...",
"width": "...",
"duration": "...", // if applicable
"image_url": "https://ytcards.demolab.com/?id=...&...",
},
{
...
},
]
```

This can be coordinated with #24 since both involve adding `output_type`.

Start by tracing how the workflow currently produces output, then review issue #24 because both proposals involve output_type. Done means accepting output_type: "json" and emitting the requested video fields plus the SVG card URL in a parseable JSON format.

Written by the indexing model from the issue text.