Normalize Japanese language code jp to ISO 639-1 ja

[ronaldtse]

Summary

IEC CDD source data uses jp for Japanese, but the browser's CSS visibility rules and the ISO 639-1 standard use ja. This mismatch made all Japanese translations invisible.

Fix: normalize at the data import boundary

Added a normalizeLanguageCodes() pipeline stage in src/lib/build/stages.ts that runs during npm run fetch-data, right after data is acquired into src/content/data/. The stage:

1. Walks every database.json under dataTarget
2. For each entity, checks every *_ml field
3. Renames the jp key to ja (preserving an existing ja key if both are present)
4. Writes the normalized JSON back

Idempotent and extensible via the LANG_ALIASES map ({"jp": "ja"} — add more if other non-standard codes surface).

Also adds ja to KNOWN_LANGS in LanguageSwitcher.vue.

Why at import, not at build-time load

The normalization happens once when data enters our ecosystem (during fetch-data), not every time loadDictionary() reads the JSON at build time. The committed/fetched data is clean; downstream consumers don't need defensive checks.

Verified on real data

[fetch-data] [normalize-language-codes] ok — renamed 80 key(s) across 8 dict(s)

After normalization: 0 jp keys remaining, 80 ja keys present across all dictionaries. Built output confirms ml-ja spans (not ml-jp) on multilingual entity pages.

Multilingual data coverage (from ../data-private/)

Dictionary	Entities	Multilingual	Languages
iec61987	12,789	10,209	de, en, fr, ja, zh
iec62683	1,861	1,855	de, en, fr, ja, zh
iec63213	220	220	de, en, fr, zh
iec63508	151	64	de, en, fr, zh
iec61360	4,491	146	de, en
iec62720	2,559	2	de, en

Test plan

• npm run check — 0 errors
• 3 new pipeline tests (renames jp→ja, preserves existing ja, skips when clean)
• npm run build — 25,476 pages built
• npm run fetch-data — "renamed 80 key(s) across 8 dict(s)"
• Verified: 0 jp keys, 80 ja keys in committed data
• Built HTML: ml-ja spans present on iec62683/p/ACE061
• Manual: visit a multilingual entity, language switcher shows JA button

[ronaldtse]

Closing in favor of opencdd/opencdd-ruby#23 — the normalization belongs in the Ruby gem at the XLS ingestion point, not in the browser pipeline.