Fix module order reset when Editor saves a lesson

[donnapep]

Summary

• When a non-admin user (e.g. Editor) saves a lesson in a course with modules owned by another user (e.g. Admin), the module ownership filters (filter_module_terms, filter_course_selected_terms) strip modules the Editor doesn't own during the read/save cycle in save_lesson_order().
• This causes all non-owned modules to be disassociated from the course and the module order to be reset.
• Fix: temporarily remove the ownership filters before reading and saving the course structure, then restore them after.

Fixes #7889

Test plan

• Run npm run test-php:wp-env -- --filter testAddLessonToCourseOrder_AsEditor_PreservesModuleOrder — should pass
• Run full test suite npm run test-php:wp-env — only pre-existing Sensei_Class_Feature_Flags_Test failures expected
• Manual: Log in as Admin, create a course with modules and lessons. Log in as Editor, edit a lesson in that course and save. Verify modules remain associated and order is preserved.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes a regression where saving a lesson as a non-admin (e.g., Editor) could unintentionally drop modules they don’t own from a course and reset the course’s module order, due to module ownership filters affecting the read/save cycle.

Changes:

• Temporarily removes module ownership term filters during Sensei_Admin::save_lesson_order() so the full course structure is read/saved.
• Adds a unit test to ensure module order is preserved when an Editor saves a lesson.
• Adds a changelog entry documenting the fix.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tests/unit-tests/test-class-lesson.php	Adds coverage to ensure Editor lesson saves do not reset _module_order or disassociate modules.
includes/class-sensei-admin.php	Removes/re-adds module ownership filters around course structure read/save to prevent module loss/order reset.
changelog/fix-broken-module-order-for-editors	Documents the bugfix in the changelog.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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[Copilot]

@donnapep I've opened a new pull request, #7911, to work on those changes. Once the pull request is ready, I'll request review from you.