chore: scaffold, CI, and the export bundle verbatim

The export bundle is the input to this port, not a sketch: the curriculum,
the tutor prompt and the five logic modules are finished and tested. They
land here byte-identical and stay that way.

  diff -r export/data data && diff -r export/lib lib
  diff -r export/prompt prompt && diff export/validate.mjs validate.mjs

data/, lib/, prompt/ and validate.mjs sit at the repo root so validate.mjs
runs verbatim with no path edits. All four are excluded from lint and
formatting — they are not ours to restyle. Types for lib/ live alongside in
types/ rather than as sibling .d.ts files, so the verbatim check stays a
plain directory diff.

CI runs the curriculum gate first, before anything else can pass:

  node validate.mjs   PASS — 0 blocking, 0 advisory

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

NOTICE.md

@@ -0,0 +1,45 @@
+# Third-party data notices
+
+Hankan's application code is the authors'. The dictionary data it ships is not, and
+carries share-alike obligations. The notices below are also surfaced in the app.
+
+## Dictionary
+
+Exactly one of these is used, depending on which source was vendored at build time.
+`app/public/dict/manifest.json` records which one produced the shipped files.
+
+### 한국어기초사전 (Basic Korean Dictionary) — preferred
+
+Published by 국립국어원 (National Institute of Korean Language).
+
+> 이 저작물은 크리에이티브 커먼즈 저작자표시-동일조건변경허락 2.0 대한민국
+> 라이선스에 따라 이용할 수 있습니다.
+
+한국어기초사전, 국립국어원 — CC BY-SA 2.0 KR
+<https://creativecommons.org/licenses/by-sa/2.0/kr/>
+
+Audio and image media referenced by the dictionary are **excluded** from that licence.
+Hankan stores media URLs only and redistributes no media files.
+
+### English Wiktionary, via kaikki.org — fallback
+
+Extracted by wiktextract (Tatu Ylonen, LREC 2022; wiktextract itself is MIT).
+Content is CC BY-SA 3.0 and GFDL, inherited from English Wiktionary.
+
+<https://kaikki.org/dictionary/Korean/> · <https://en.wiktionary.org/>
+
+## Frequency data
+
+hermitdave/FrequencyWords, `content/2018/ko` — derived from OpenSubtitles2018 via OPUS.
+Word list content is CC BY-SA 4.0; the project's code is MIT.
+
+<https://github.com/hermitdave/FrequencyWords>
+
+## A note on licence compatibility
+
+CC BY-SA 2.0 KR and CC BY-SA 4.0 are not automatically compatible in a single derived
+work. Hankan therefore keeps frequency data as a separately-attributed adjunct: it
+populates the `lemma.freq_rank` column only, and is not merged into the dictionary
+content itself. Both notices ship together.
+
+Share-alike attaches to the derived dictionary data, not to Hankan's application code.