AO3-6591: Move imported_from_url to a new table with different varian…

[gmjimenezc]

…ts in different columns

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Issue

https://otwarchive.atlassian.net/browse/AO3-6591

Purpose

• Creates a new work_import_urls table to store import URLs separately from the works table, with pre-computed URL variant columns (minimal, minimal_no_protocol_no_www) for fast exact-match lookups
• Eliminates the slow LIKE query in Work.find_by_url — the old 3-tier fuzzy matching (exact → variants → LIKE with Ruby filtering) is replaced by simple find_by calls against indexed variant columns
• Moves all URL lookup logic into a new WorkImportUrl model, including caching, reducing complexity in the already-bloated Work model
• Removes the imported_from_url column from the works table entirely, replacing it with a has_one :work_import_url association and a delegated imported_from_url reader method
• Updates the Elasticsearch indexer to read imported_from_url via the association method instead of the column
• Updates StoryParser to build a WorkImportUrl record when importing works
• Updates the Open Doors tools controller and rake task to create/update WorkImportUrl records directly
• Updates the API v2 works controller to query the new table for import URL searches
• Adds a backfill rake task (work_import_urls:backfill) to populate the new table from existing data before the column is removed
• Adds specs for the new model covering variant computation, validations, URL matching, and caching

Testing Instructions

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References

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Credit

warlockmel (she/her)