fix: iframe Editor Compatibility

[chickenn00dle]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Closes https://linear.app/a8c/issue/NPPM-2586/newspack-newsletters-iframe-editor-compatibility

How to test the changes in this Pull Request:

1. Ensure ONLY the main plugin, blocks, newsletters, and popups are the only Newspack extensions active and are all on the fix/iframe-editor-compatibility branch.
2. Smoke test blocks in the editor + frontend (You can find a list in the linked linear issue)

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[Copilot]

Pull request overview

This PR aims to improve Gutenberg iframe-based editor compatibility for Newspack Newsletters blocks by aligning block registration/assets with block.json + API v3 patterns and by switching editor asset enqueueing to a hook that runs inside the iframe.

Changes:

• Migrate the Share block to block.json metadata-based registration (apiVersion 3).
• Update Posts Inserter editor wrapper to use useBlockProps and add block.json schema/apiVersion.
• Switch editor-related asset enqueues from enqueue_block_editor_assets to enqueue_block_assets (with is_admin() guards), and bump some blocks to apiVersion: 3.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/editor/blocks/share/index.js	Switches Share block registration to metadata/settings pattern using block.json.
src/editor/blocks/share/block.json	Adds Share block metadata/attributes/supports (apiVersion 3).
src/editor/blocks/posts-inserter/index.js	Uses useBlockProps + classnames for consistent wrapper props/classes.
src/editor/blocks/posts-inserter/block.json	Adds $schema and apiVersion: 3 to metadata.
src/editor/blocks/ad/block.json	Bumps block API version to 3.
src/blocks/subscribe/block.json	Bumps block API version to 3.
includes/class-newspack-newsletters-editor.php	Moves editor assets enqueue hook to enqueue_block_assets and renames method accordingly.
includes/class-newspack-newsletters-blocks.php	Moves blocks assets enqueue hook to enqueue_block_assets and renames method accordingly.

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[github-actions]

Hey @chickenn00dle, good job getting this PR merged! 🎉

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[github-actions]

🎉 This PR is included in version 3.29.0-alpha.1 🎉

The release is available on GitHub release

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