Sync course sections and course materials (documents, folders) via the Schoology REST API, independent of grades or roster data

Steps

1. Create or update sections under a course by POSTing to the sections endpoint with update_existing=1; without that flag, creating a section whose section_code + grading_periods already matches an existing section fails instead of updating it.
2. Retrieve a course's existing sections with a paged GET, or fetch by school code by passing a comma-separated list of section school codes (up to 50 per request).
3. Organize course content with the course-folder resource: a folder request returns its contents and any child folders, a folder with a parent object points back to its parent, and folder id=0 represents the course's root.
4. Create simple content items with the documents endpoint — a document must include an attachment, since documents are defined as content items with exactly one attachment.
5. Append the with_tags query string to document/material list requests when each item's associated tags need to be returned alongside the content.
6. When decommissioning sections in bulk, delete via the section_ids query parameter with up to 50 comma-separated Schoology IDs per call, batching larger cleanups across multiple requests.