kernel(rite-ef): replace unearned/retracted citations with verified ones

Four citation problems, all resolved against the primary scans
(docs/research/*.pdf via pdftotext):

1. temporal_ef.ml's Ember-day date-derivation comment still carried a
   retracted note claiming the scans have no numbered-paragraph statement
   of the rule. Register §3a corrected this in an earlier commit (the
   search used the genitive "Quatuor Temporum"; the rubric heading is the
   nominative "Quatuor Tempora") and the register's own words warn "a
   false 'not in the source' note is worse than no note" -- the code
   still carried the retracted note verbatim. Replaced with the verified
   citation and the primary Latin.

2. temporal_ef.ml cited RG 71 for "Advent I is the Sunday nearest 30
   November". RG 71 is a season-boundary citation only ("a I Vesperis
   dominicae I Adventus..."); it does not say which Sunday opens the
   season. The actual rule is RG 20 (Caput III, "De Dominicis"):
   "Dominica I Adventus ea est, quae cadit die 30 novembris vel est ipsi
   proximior" -- verified against the scan and added to the register.
   Behaviour was always correct; only the citation was borrowed.

3. RG 88 ("de Litaniis minoribus nihil fit in Officio") is cited five
   times across code and tests, load-bearing twice (why Rogation days
   take their season's ordinary ferial class; why privilege_of lets them
   fall through to Ordinary), but appeared nowhere in the register. RG 67
   and RG 69 were likewise cited at expected-divergences-missalemeum.sexp
   (M11) without register backing. All three verified against the scan
   and added to the register's §4 (Octaves / Rogations subsections).

4. Two citations flagged for re-verification, both CONFIRMED accurate
   against the primary scan (word for word):
   - precedence_ef.ml's RG 32 "si impeditur, commemoratur" (the sole
     textual basis for treating a vigil as always-commemorated once RG 33
     doesn't omit it outright) -- the register previously stated RG 32
     only as "same pattern as RG 31", not verbatim; the full sentence is
     now in the register too.
   - precedence_ef.ml's RG 111(b) full sentence (the sole textual basis
     for the shipped Sunday rank-floor fix) -- the register previously
     carried only the fragment "de festo II classis"; the full sentence
     is now there.
   - temporal_ef.ml's RG 91 entry 7 "feria IV cinerum et II, III et IV
     Hebdomadae sanctae" (the sole justification for stopping the I-class
     ferias at Wednesday) was also checked and matches the scan exactly;
     left as-is (already correctly cited), noted in the report.

Bonus finding while re-verifying RG 20: RG 17(d), same chapter, states
"festum D. N. Iesu Christi Regis, celebrandum dominica ultima mensis
octobris" -- primary-source confirmation that Christ the King falls on
the last Sunday of October. This was the register's one
oracle-backed-but-not-primary-verified rule (CLAUDE.md's own carried-item
language); it no longer is. Updated temporal_ef.ml's christ_the_king
comment and closed the item in register §6.

No behaviour change: every edit here is a comment/citation change to
already-correct code. Verified byte-identical `colitur day` output across
1583, 1900, 1902, 2008, 2011, 2026, 2038, 9999. 259/259 tests green.

0 files changed, 0 insertions, 0 deletions