Publicize to Bluesky: support hashtags in Publicized posts

[jeherve]

Impacted plugin

Jetpack, Social

Quick summary

Bluesky supports hashtags, just like Twitter does. Hashtags in posts are automatically linked and allow for a search:

However, hashtags posted via Publicized posts are not auto-linked:

Steps to reproduce

1. Start with a site that's connected to WordPress.com.
2. Go to Jetpack > Settings > Social
3. Connect your site to your Bluesky account.
4. Go to Posts > Add New
5. Write a new post
6. Hit publish
7. In the pre-publish panel, customize your Publicize message to include a hashtag.
8. Confirm publish

A clear and concise description of what you expected to happen.

I would expect the post that gets posted to Bluesky to include a linked hashtag.

What actually happened

The hashtag is not linked.

Impact

All

Available workarounds?

No but the platform is still usable

If the above answer is "Yes...", outline the workaround.

No response

Platform (Simple and/or Atomic)

Simple, Atomic, Self-hosted

Logs or notes

This was also reported in #30460 (comment)

[github-actions]

OpenAI suggested the following labels for this issue:

• [Feature Group] User Interaction & Engagement: The issue is related to how users engage with social media and how hashtags enhance that interaction in posts.
• [Feature] Publicize: The issue directly concerns the Publicize feature, which is responsible for sharing content to social media platforms, including Bluesky.
• [Feature] Social Media Integration: The problem involves integrating with Bluesky, a social media platform, and enhancing its functionality with hashtags.