feat(snapshots): Restructure sidecar JSON to match ingestion schema

[runningcode]

Summary

Aligns the per-snapshot sidecar JSON with the ingestion JSON Schema by organizing fields into the defined buckets:

• Top level: display_name, group, diff_threshold
• tags (appearance / render inputs): preview_name, locale, device, font_scale, api_level, width_dp, height_dp, show_system_ui, show_background, ui_mode
• context (preview identity / location): image_file_name, class_name, method_name

Notable behavior changes:

• The old night_mode boolean is gone. Dark/light state is now emitted as a ui_mode tag, only when the @Preview(uiMode = …) bits explicitly set UI_MODE_NIGHT_YES → "dark" or UI_MODE_NIGHT_NO → "light". The common UI_MODE_NIGHT_UNDEFINED case (the default for unannotated previews) yields no ui_mode tag.
• preview_name (the @Preview(name = …) label) moves from top level into tags.
• tags is omitted when empty; context is always present.

Implementation notes:

• The sidecar writer is emitted as a string literal inside the generated Paparazzi test (GenerateSnapshotTestsTask.kt), so the change lives in that template.
• The hand-rolled JSON writer is replaced with a tiny recursive renderJson(value, indentLevel) that handles String, Number, Boolean, and Map<*,*> — no new dependencies.

Example output:

{
  "display_name": "FooPreview",
  "group": "main",
  "tags": { "preview_name": "Dark", "locale": "en", "font_scale": 1.5, "ui_mode": "dark" },
  "context": {
    "image_file_name": "com.example.FooPreview",
    "class_name": "com.example.Foo",
    "method_name": "FooPreview"
  }
}

#skip-changelog

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 67d6904

[rbro112]

Make sure to pass this through as uiMode in context

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 6acdeab. Configure here.}