fix(of): correct memorial readings (ferial fallback) + Lord-feast class

Validation vs USCCB (Catholic Readings API) caught two bugs:
- Obligatory memorials were keyed by their own slug, freezing ONE year's ferial
  (a memorial's fixed date lands in a different Ordinary-Time week each year), so
  most weekday memorials showed the wrong week's reading. Now memorials are
  skipped in the harvest and fall back to the day's ferial slug at runtime -> the
  correct week's reading. (Proper-reading memorials show the permitted ferial;
  their propers are a later refinement.)
- gen-sanctoral classOf missed feasts of the Lord whose title says 'Holy Cross'
  (not 'of the Cross') etc., so the Exaltation of the Cross (and Transfiguration,
  Presentation) did not displace an Ordinary Sunday. Fixed the Lord/BVM class
  inference; the Cross now correctly displaces the Sunday and shows its proper.

USCCB agreement on the sampled 2025 window rose to ~92%; residual diffs are
proper-reading memorials (Guardian Angels/Sorrows gospels), citation-granularity
(same reading, different verse range), and week numbering around feast-displaced
Sundays -- documented as known refinements.

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