Name Greek Sundays after the Gospel, and fix Clean Week feasts

[brianglass]

Part of the remaining title and fasting differences from #228. A second PR will follow for the missing forefeast and afterfeast labels and the Greek-dated commemorations.

Greek Sunday titles

Greek usage names ordinary Sundays for the Evangelist being read rather than counting them from Pentecost.

• GreekDay now titles them "Nth Sunday of Matthew/Luke", numbered from the Gospel actually served (gospel_pdist), so the Lukan jump and the Theophany interpolation carry through.
• The Forefathers are the 11th Sunday of Luke, Zacchaeus the 15th, and the interpolated 17th of Matthew is "Sunday of the Canaanite Woman".
• Sundays known only by a neighbouring feast (before/after Nativity and Theophany) take that feast as their title.

Validation: antiochian.org agrees on 123 of 125 such Sundays across its 2018-2026 harvest. The other two are January 2024, where antiochian.org and goarch.org read different Gospels and the title follows ours (goarch.org's).

This covers 13 of the 19 headline differences in #228, all but the forefeasts, the leavetaking and Phocas.

July Fathers Sunday

Greek practice keeps the Fathers of the 4th Ecumenical Council where Slavic keeps the 1st Six Councils. Following the Oct 1 Protection pattern, row 802 becomes slavic and a new greek row 949 carries the 4th Council. I spliced the fixture by hand rather than re-dumping it, to avoid reordering about 22k lines.

Clean Week fasting

GOA lets a rank-4 feast keep its wine and oil on Clean Tuesday to Friday; Clean Monday stays strict. goarch.org's 2025-2035 calendar shows this on all four such days:

Date	Day	goarch.org
2026-02-24	Tue	wine and oil
2031-02-24	Mon	strict
2033-03-09	Wed	wine and oil
2034-02-24	Fri	wine and oil

Previously Clean Week's "no overrides" cap held all four strict. The goarch.org fasting audit goes from 3678 to 3681 of 3683 days. The other two contradict goarch.org's own pattern in other years and are documented in docs/greek-fasting.md.

Holy Saturday stays wine only (Typikon and Antioch), as decided.

Unchanged

Slavic titles and fasting. The fasting golden file changes on exactly one day, 2026-02-24 Greek.

Tests

• New: TestGreekSundayTitles, plus a Clean Week case in TestGreekFasting.
• 257 tests run; all pass locally except MonthCacheTestCase.test_cache_hit_skips_computation, which fails on main too because the gitignored local_settings.py uses DummyCache.

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