Requirements - Source Monitor

Implement the Confirm step that shows a summary table of selected sources and the applied bulk settings for final review.
When confirmed, enqueue a background import job that creates sources individually, records per-source success/failure and skipped duplicates, and persists an ImportHistory record with results.
After job completion, ensure the user can view a static confirmation message on the Sources index with counts and a table of failures; guarantee that ImportHistory entries are queryable from the UI later.

Use Solid Queue for the import background job; the job should iterate selected sources, create sources individually (reusing Sources creation logic/service objects), capture and persist errors per source, and skip duplicates discovered by feed URL matching.
Create an ImportHistory ActiveRecord model/migration with JSONB columns for imported_sources, failed_sources, skipped_duplicates, bulk_settings, started_at and completed_at. Implement ImportHistory to reference the performing user using standard integer-based ActiveRecord IDs (i.e., user_id as an integer foreign key). Ensure migrations and model associations use Rails default integer id conventions rather than UUIDs.
Broadcast import completion via Turbo Streams (targeting Sources index or an ImportHistory feed) so users see static messaging and results; Ensure the static confirmation is available on next visit to Sources index even if the user navigated away during processing.
Ensure transactional and idempotency considerations for creation logic: handle ActiveRecord::RecordNotUnique or race conditions gracefully and record appropriate failure/skipped state.
Enforce admin-only access and strong parameter sanitization.