chore: Halkyon Learn moves into apps/learn

Its server, client, app and curator, and the tools that write its
assets (maps, Anki fixtures, icons), as they are; paths are fixed in
the commits that follow.

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

apps/learn/halkyon_learn_curator/test/fixtures/cedict-characters-sample.txt

@@ -0,0 +1,19 @@
+# CC-CEDICT
+#! date=2026-10-14T07:20:00Z
+了 了 [le5] /(completed action marker)/(modal particle indicating change of state, situation now)/(modal particle intensifying preceding clause)/
+以後 以后 [yi3 hou4] /after/later/afterwards/following/later on/in the future/
+們 们 [men5] /plural marker for pronouns, and nouns referring to individuals/
+后 后 [hou4] /empress/queen/(archaic) monarch/ruler/
+學 学 [xue2] /to learn/to study/to imitate/science/-ology/
+學習 学习 [xue2 xi2] /to learn; to study/
+後 后 [hou4] /back/behind/rear/afterwards/after/later/post-/
+我們 我们 [wo3 men5] /we; us; ourselves/
+水 水 [shui3] /water/(after a name) ... River/to swim (used mostly in 會水|会水[hui4 shui3] and 水性[shui3 xing4])/(coll.) lacking in substance; shoddy/(bound form) additional cost; extra income/classifier for washings of a garment/
+為了 为了 [wei4 le5] /for; for the purpose of; in order to/
+皇后 皇后 [huang2 hou4] /empress/imperial consort/
+瞭 了 [liao3] /(bound form) clear in one's mind; to understand clearly/
+瞭解 了解 [liao3 jie3] /variant of 了解[liao3 jie3]/
+行 行 [xing2] /(bound form) to walk; to go; to travel/(literary) trip; journey; visit/(bound form) temporary; makeshift/(bound form) current; in circulation/(bound form) to do; to perform/capable; competent/all right; OK!; will do/behavior; conduct (Taiwan pr. [xing4])/(literary) about to; soon/
+說 说 [shuo1] /to speak; to talk; to say/to explain; to comment/to scold; to tell off/(bound form) theory; doctrine/
+這 这 [zhe4] /(pronoun) this; these/(bound form) this; the (followed by a noun)/(bound form) this; these (followed by a classifier) (in this sense, commonly pr. [zhei4], esp. in Beijing)/
+銀行 银行 [yin2 hang2] /bank/CL:家[jia1],個|个[ge4]/