2019-09: isKeywordEnabled does an O(vocabularies) scan per keyword

[aeschli]

Found while reviewing #308 (JSON Schema 2019-09 support).

Problem

isKeywordEnabled in src/services/vocabularies.ts iterates Object.entries(vocabularyKeywords) (all vocabularies and their keyword arrays) for every keyword check, and this runs per keyword per node during validation when vocabularies are active.

for (const [vocabUri, keywords] of Object.entries(vocabularyKeywords)) {
    if (keywords.includes(keyword) && activeVocabularies.has(vocabUri)) {
        return true;
    }
}

Suggested direction

Precompute a reverse keyword -> Set<vocabUri> map once at module load and do a single lookup.

Severity

Low — minor perf, only when activeVocabularies is present.