feat: bulk add courses to base catalog

[ccantillo]

Bulk add courses to Base Catalog

Summary

Administrators could only add one course at a time to the Base Catalog, which
was impractical when dealing with dozens or hundreds of courses. This PR adds a
Bulk Add Courses page to the BaseCatalog admin interface, featuring a
visual dual-panel course picker with search, select, and batch-add capabilities.

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What changed

partner_catalog/admin.py

• Added BulkAddCoursesForm — a Django form using the FilteredSelectMultiple
  widget, which renders the built-in Django admin dual-panel picker.
• Added get_urls() to BaseCatalogAdmin to register a custom admin route:
  /<uuid>/bulk-add-courses/
• Added bulk_add_courses_view() — handles GET (render picker) and POST (save
  selected courses). Courses are added via BaseCatalogCourse.get_or_create,
  so duplicate submissions are safe.
• Updated add_course_button (detail page) to show two buttons:
  + Add Single Course (existing flow) and + Bulk Add Courses (new).
• Updated add_course (list view column) to link directly to the bulk-add page.

partner_catalog/templates/admin/partner_catalog/basecatalog/bulk_add_courses.html

New admin template extending admin/base_site.html with proper CSS
(admin/css/forms.css) and JS (jsi18n + combined admin+form media) loading.

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How the picker works

The Available Courses panel (left) lists all courses not yet in the
catalog, sorted alphabetically. The Chosen Courses panel (right) holds the
courses selected for addition.

Action	How
Select a single course	Click it in the left panel
Select multiple courses	Ctrl + click (or Cmd + click on Mac) each course
Move selected to right	Click the Choose selected Courses arrow button
Move all visible to right	Click Choose all Courses
Deselect / remove	Select in right panel → Remove selected Courses
Remove all chosen	Click Remove all Courses
Filter courses by name	Type in the Filter box above either panel — results update instantly

Important: the Choose all Courses button adds only the courses
currently visible after filtering. Type a search term first and then
click "Choose all" to bulk-select only the matching results.

Once the desired courses are in the right panel, click Add Selected Courses
to save. The admin redirects back to the BaseCatalog detail page and shows a
success message with the count of courses added.

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Files changed

Repo	File	Change
openedx-corporate	partner_catalog/admin.py	BulkAddCoursesForm, get_urls, bulk_add_courses_view, updated buttons
openedx-corporate	partner_catalog/templates/admin/partner_catalog/basecatalog/bulk_add_courses.html	New template for the bulk-add page

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Testing

1. Go to /admin/partner_catalog/basecatalog/.
2. Click + Bulk Add Courses in the list view, or open a catalog and click
   the green + Bulk Add Courses button.
3. The picker opens showing all courses not yet in the catalog.
4. Use the Filter box, Ctrl + click to multi-select, and the arrow buttons to
   move courses to the right panel.
5. Click Add Selected Courses — redirects back to the catalog detail page
   with a success message confirming how many courses were added.
6. Confirm the Total Courses count on the detail page has increased.
7. Re-open the bulk-add page and confirm the newly added courses no longer
   appear in the Available Courses panel.

[igobranco]

@ccantillo in future please add screenshots!

I have tested locally and it seems to be working fine.

Nevertheless, this is not good enough! The functionality requested needs to be improved. We can't just "Add Bulk Courses" but also we need to improve it so it is a "Manage Bulk Courses".
The both select multiples need to work has User Groups on Django. Like the use case: /admin/auth/group/1/change/

Screenshots of the corporate module:

Screenshot of Manage User Group:

On refresh it still loads the existing groups.

[igobranco]

Transform it to be like Manage Bulk Courses.
Currently I didn't find a way to remove courses.

[ccantillo]

Transform it to be like Manage Bulk Courses. Currently I didn't find a way to remove courses.

Hi @igobranco, thanks for the feedback!

Reworked the implementation to match the auth/group pattern. The "Bulk Add Courses" separate page is gone — the FilteredSelectMultiple widget now lives directly on the BaseCatalog change form, pre-populated with the catalog's current courses on load.

A single Save now handles both additions and removals: it diffs the selected set against the current BaseCatalogCourse entries, creates the new ones (preserving added_by/added_at metadata), and deletes the removed ones.

[igobranco]

LGTM ✔️