feat(scaffold-core): classify/ module — patterns, classifier, enricher, bindings, quality

[stackbilt-admin]

Part of #212.

Scope

Extract and isolate the classification layer from stackbilt-web/src/lib/scaffold-core.ts into packages/scaffold-core/src/classify/.

Files to create

File	Source	Responsibility
patterns.ts	PATTERNS array, PatternDef type	9 pattern definitions with scoring functions and trait sets
classifier.ts	choosePattern(), keywordScore(), lineSeed()	Pattern selection, confidence scoring
enricher.ts	extractEnrichedPrd(), injectPrdSections(), STACK_TOKENS, DOMAIN_ENTITY_PATTERNS, MANAGEMENT_PATTERNS	Domain entity + stack token extraction from free-form intention
bindings.ts	inferBindings()	Maps intention keywords to CF binding names (d1, kv, r2, do, ai)
quality.ts	QualityProfile, inferQualityProfile()	Derives tenant/payments/streaming/storage/jwt/oauth/rate-limit profile
index.ts	—	Re-exports classify(intention) → ClassifyResult

Key invariant

classify/ has zero inbound deps within the package — pure functions, pure data. Must be importable standalone with no side effects.

Tests

Migrate stackbilt-web/src/lib/__tests__/scaffold-domain-fixtures.test.ts here.

[stackbilt-admin]

Work shipped in @stackbilt/scaffold-core@1.1.0 (charter#212, PRs #219-222). Closing stale tracking issue.