New BookorbitConfig section (enabled, URLs, OPDS user; password via
DAILY_EPUB_BOOKORBIT__OPDS_PASS), its settings-dashboard group and secret
masking, migration 0005 adding bookorbit_book_id/bookorbit_file_id to
issues with Db::set_bookorbit_ids, and README rows for the new keys.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Va5eMEmWEnjMXBsBob5FDW
