Merge branch 'import-improvements' into 'main'

app/controllers/admin/conferences_controller.rb

app/jobs/conference_import_job.rb

app/jobs/fetch_conference_data_job.rb

app/models/conference.rb

app/models/import_history.rb

app/views/admin/conferences/edit.html.erb

app/views/admin/conferences/import_error.html.erb

app/views/admin/conferences/import_history.html.erb

app/views/admin/conferences/import_progress.html.erb

app/views/admin/conferences/select_relevant_stages.html.erb

config/cronotab.rb

config/routes.rb

...4204757_add_import_timestamps_and_error_to_conferences.rb

db/migrate/20250304204807_create_import_histories.rb

db/schema.rb

test/fixtures/import_histories.yml

test/models/import_history_test.rb