refactor: change SnapJSON to output raw JSON instead of Go maps
SnapJSON now uses json.MarshalIndent to produce properly formatted raw JSON
strings in snapshots, rather than converting to Go map representations. This
provides cleaner, more readable snapshots that match the actual JSON format
users work with.
Benefits:
- Snapshots now show actual JSON syntax users recognize
- Consistent with standard JSON formatting (2-space indentation)
- Clearer diffs when JSON structure changes
- Better alignment with how JSON is typically represented