feat(curator): Tatoeba's sentences as examples in every new language

JMdict brings Tatoeba's sentences for Japanese; the other languages'
dictionaries had none (CC-CEDICT) or Wiktionary's own, often
quotations. Each file now takes Tatoeba's sentences of the week (its
per-language exports, CC BY 2.0 FR) as its entries' first examples,
which become a card's hints: each sentence with a translation into the
dictionary's meaning language goes to the entries its words find, cut
as the app cuts a line of subtitles (at spaces, Korean's particles off,
Chinese by its longest words), up to three for each, those using the
word as its headword writes it first (Haus rather than zu Hause; 学习
rather than 學習 in the simplified dictionary), then those nearest seven
words long. German's common words nearly all get some (8,849 of
9,292), in ten seconds and under 300 MB; a dictionary whose sentences
can't be had keeps its words. `curate tatoeba` does the same for a file
made by hand.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_curator/test/fixtures/README.md

@@ -44,3 +44,10 @@ the extraction is Tatu Ylonen's Wiktextract (<https://kaikki.org>).
 2026-10-13): 中国, 了, 女儿, 学习, 书, 熊猫, 略, 的, 说, 银行, 和 and 咊, an old
 variant of 和, with their readings. CC-CEDICT is by MDBG and its contributors, CC BY-SA 4.0
 (<https://www.mdbg.net/chinese/dictionary?page=cc-cedict>).
+
+`tatoeba-*.tsv` hold a few lines of Tatoeba's exports of 2026-10-10
+(<https://downloads.tatoeba.org/exports/per_language/>): German, Chinese and
+Korean sentences using Haus, aß, Straße, 学习, 집에서 and 학생이 (and one of each
+without an English translation), the links to their English translations, and
+those translations. The sentences are by Tatoeba's contributors, CC BY 2.0 FR
+(<https://tatoeba.org/en/terms_of_use>).