fix: Prevent WordPress embed block share overlay cutoff

[Sukhendu2002]

Fixes: https://github.com/WordPress/gutenberg/issues/67148

What?

This PR fixes an issue where the share overlay in WordPress embed blocks gets truncated in the editor when embedding posts with minimal content while displaying correctly on the published site.

Why?

When embedding posts with minimal content using the WordPress embed block, the share overlay gets cut off in the editor interface, creating an inconsistent experience between the editor and the published site.

How?

Added minimum height property to the embed block's iframe to ensure sufficient space for the share overlay to display completely, regardless of the embedded content's length.

Testing Instructions

1. Create a new post with minimal content (just title and short paragraph)
2. Open a different post in the editor
3. Add a WordPress embed block
4. Paste the URL of the minimal content post into the embed block
5. Verify that the share overlay is fully visible in the editor
6. Save and preview the post
7. Verify that the overlay appearance matches between editor and published view

Screenshots or screencast

Before

After

[github-actions[bot]]

:wave: Thanks for your first Pull Request and for helping build the future of Gutenberg and WordPress, @Sukhendu2002! In case you missed it, we'd love to have you join us in our Slack community.

If you want to learn more about WordPress development in general, check out the Core Handbook full of helpful information.

[github-actions[bot]]

Warning: Type of PR label mismatch

To merge this PR, it requires exactly 1 label indicating the type of PR. Other labels are optional and not being checked here.

• Type-related labels to choose from: [Type] Automated Testing, [Type] Breaking Change, [Type] Bug, [Type] Build Tooling, [Type] Code Quality, [Type] Copy, [Type] Developer Documentation, [Type] Enhancement, [Type] Experimental, [Type] Feature, [Type] New API, [Type] Task, [Type] Technical Prototype, [Type] Performance, [Type] Project Management, [Type] Regression, [Type] Security, [Type] WP Core Ticket, Backport from WordPress Core, Gutenberg Plugin.
• Labels found: First-time Contributor.

Read more about Type labels in Gutenberg. Don't worry if you don't have the required permissions to add labels; the PR reviewer should be able to help with the task.

[github-actions[bot]]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: Sukhendu2002 <sukhendu2002@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.