Theme: Fix the live demo for not WP.com themes

[arthur791004]

Related to #71780

Proposed Changes

• Fix the live demo doesn't work for themes not belonging to WP.com as
  1. The demo site doesn't have the jetpack-iframe-embed plugin, so we might not have enough information
  2. The ancestor (Calypso) violates the Content Security Policy of the 3rd party demo site
• Hence, open the live demo URL directly if the theme is not a WP.com theme or 3rd party theme
• Moreover, this PR also makes the behavior of the Live demo consistent between
  1. Theme Showcase
  2. The Live demo button on the Theme Details page
  3. The behavior when you click the preview on the Theme Details page

Testing Instructions

• Go to Theme Showcase
• On the list screen, ensure the live demo works for free, premium, community, and partner themes
• Go to the theme details page, ensure the live demo works for those themes as well

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-ajp-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:commit-9d533b66f4885ceb62e7de3f60d0a5e22e7747fe

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:commit-9d533b66f4885ceb62e7de3f60d0a5e22e7747fe&env=jetpack

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~44 bytes added 📈 [gzipped])

name    parsed_size           gzip_size
theme        +134 B  (+0.0%)      +44 B  (+0.0%)
themes       +124 B  (+0.0%)      +42 B  (+0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[miksansegundo]

👍

This partner theme preview is clickable and opens the theme in a new tab.

Screen.Recording.2566-08-08.at.16.53.33.mov

I expected that when I click on the Dotcom theme previews the demo site opens in the modal but they are not clickable. Is this expected?

Cultivate by Automattic

Screen.Recording.2566-08-08.at.17.00.04.mov

Issue by Automattic

Screen.Recording.2566-08-08.at.17.00.30.mov

[arthur791004]

Yes, they are expected.