Add Goodreads library import

[TrapEmAll]

Summary

Adds a Goodreads library import path that reuses Listenarr's existing library add workflow.

• adds POST /api/v{version}/library/import/goodreads
• supports Goodreads export CSV via csvContent and public Goodreads list/shelf URLs via url
• parses Goodreads books into existing audiobook metadata and imports them through ILibraryAddService
• returns per-item added/skipped/error results with summary counts
• documents the endpoint and import limitations in the README

Notes

CSV import is the most reliable path because Goodreads exports include ISBNs, which Listenarr can use for existing duplicate detection. Public Goodreads URL import is best-effort HTML parsing and may only provide title, author, Goodreads ID, and source URL. Goodreads IDs are returned in the import result but are not persisted as a first-class identifier because the current identifier enum does not include Goodreads and adding one would require a schema migration plus UI/API contract expansion.

Validation

• dotnet test tests\Listenarr.Tests.csproj --no-restore --filter Goodreads
• dotnet build listenarr.slnx --no-restore