Release: v3.10.0-beta.1

[code-snippets-bot]

Release Preparation for v3.10.0-beta.1

This pull request prepares the release for version v3.10.0-beta.1.

Generated by:

• Workflow: (Release): Prepare Release Pull Request
• Run: #187

Next steps:

• Write the changelog and readme entries (auto-generation was disabled for this run)
• Verify version numbers are correct

[imantsk]

Changelog reconciliation notes for this release:

• Beta releases do not need their own change entries. This beta may instead carry the upcoming stable's feature list under a 3.10.0 (TBA) heading.
• The existing 4.0.0-beta.1 entries in CHANGELOG.md and readme.txt describe what now ships as 3.10 — fold them into the 3.10.0 (TBA) list rather than leaving both.
• The plugin header briefly read 3.10.0-beta.1-beta.1 from a version-bump defect in the shared workflow; corrected in 26098d3 and fixed upstream so it cannot recur.