feat: localized instrument catalogs

[gierschv]

What

Adds localized instrument names to the public catalog. Every non-English locale ships as a complete, drop-in catalog under data/i18n/<lang>.json — 27 locales.

Each locale file has the exact same shape and instrument IDs (same order) as data/instruments.json; only name/shortname (and group names) are localized, falling back to English wherever no translation exists. Consumers load the single file for their locale — nothing to merge.

import type { InstrumentsFile } from '@flat/instruments';
import fr from '@flat/instruments/data/i18n/fr.json' with { type: 'json' };

(fr as InstrumentsFile).groups
  .flatMap(g => g.instruments)
  .find(i => i.id === 'brass.trumpet'); // → { …, name: "Trompette", shortname: "Tromp." }

Changes

• data/i18n/*.json — 27 localized catalogs (da, de, en-GB, es, fi, fil, fr, fr-CA, hi, id, it, ja, ja-HIRA, ko, ms, nb, nl, pl, pt, pt-BR, ro, ru, sv, tr, zh-Hans, zh-HK, zh-TW).
• package.json — expose ./data/i18n/*.json via the exports map.
• scripts/validate.mjs — validate every locale catalog against the JSON Schema and assert it exposes the same instrument IDs, in the same order, as the English catalog.
• README.md — document localized usage.
• test/i18n.test.mjs — structural-parity + real-translation tests.

The English data/instruments.json and the runtime JS API are unchanged.

Source

These files are generated from instruments-meta's localized fixtures via its sync-public-instruments script (separate GitLab change). To regenerate: pnpm sync-public from instruments-meta.

Verification

• pnpm validate → 205 instruments / 11 groups, plus 27 localized catalogs
• pnpm test → 12 passed