WIP: implements backend, frontend UX, and basic UI for community library

[GoldenLin9]

Features

For all authenticated users

• Browse a grid of published instances with infinite-scroll pagination
• Filter by widget type, category (Math, Science, English, etc.), and course level (Intro / Intermediate / Advanced)
• Search by instance name
• Sort by Newest, Most Copied, Most Liked, or A–Z
• Featured section highlights admin-selected content when no filters are active
• Preview snapshots in the widget player without altering the original instance
• Like / unlike entries (toggle)
• Copy ("Use This") duplicates the snapshot into the user's My Widgets
• Report entries with a reason (inappropriate / incorrect / spam / other) and optional details
• Pull Latest from Library lets users who copied a widget overwrite their copy's name and questions with the latest snapshot (confirmation dialog, error handling for unpublished entries)

For instance owners

• Publish to Library dialog in My Widgets with category and course-level selectors
• Update in Library creates a new snapshot from the current qset without unpublishing
• Remove from Library unpublishes cleanly (cascades snapshots, no orphan data)

For support / superusers

• New Community Library tab in Instance Admin showing reported and banned entries
• Moderation section on selected instance: toggle Featured, Ban/Unban, view report/copy/like counts
• Auto-ban threshold: entries hitting 5 reports are auto-hidden with admin notification

Architecture

• Snapshot-based: Publishing creates an immutable snapshot of the name and qset. Previews, copies, and pulls always use snapshots, never the live data
• Copy: "Use This" duplicates with FK back to the source entry for pull-from-library
• Scoring override: Snapshot preview score screens swap the qset in memory before scoring so the entire pipeline uses snapshot data

Testing

• Run python manage.py test api.tests.test_community_library_views
• Publish an instance → select category/course level → verify it appears in the library
• Edit the original instance's qset → verify library preview still shows the old snapshot
• "Update in Library" → verify new snapshot is served on preview
• Unpublish → verify entry is removed from community library
• Search, filter by widget/category/course level, and each sort option
• Like / unlike → verify count updates and persists
• Copy → verify new instance in My Widgets with snapshot name and qset, copy_count bumps
• Copy → verify "Pull Latest from Library" button appears in action menu
• Pull Latest → verify name and qset update to match latest snapshot
• Unpublish source → verify "Pull Latest" button disappears on copied widget
• Report same entry twice from one account → second attempt returns 400
• Report 5 times from different users → entry auto-banned, admins notified
• Instance Admin → Community Library tab → view reported/banned entries, toggle Featured, Ban/Unban