feat(core-consent): scaffold package with types, IConsent, withConsent brand wrapper

- Add packages/core-consent with ConsentCategory, ConsentState,
  UserConsentState types and IConsent interface
- Add withConsent wrapper attaching __consentChecked brand at bind time;
  unit tests assert brand attachment and factory passthrough
- Add ConsentChecked<F> type to core-shared/conformance/brands.ts and
  isConsentChecked helper to brand-runtime.ts
- Extend FeatureManifest with requiresConsent?: readonly string[] field
- Extend assertFeatureConformance to require __consentChecked brand when
  requiresConsent.length > 0; synthetic fixture tests cover pass/fail cases
- Propagate __consentChecked in withSpan PROPAGATED_BRANDS so the outermost
  binding carries the brand

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-shared/src/conformance/index.ts

@@ -1,4 +1,9 @@
-export type { Instrumented, Captured, Analyzed } from "./brands";
+export type {
+  Instrumented,
+  Captured,
+  Analyzed,
+  ConsentChecked,
+} from "./brands";
 export type { FeatureManifest, UseCaseManifest } from "./define-feature";
 export { defineFeature } from "./define-feature";
 export type {
@@ -23,6 +28,7 @@ export {
   isCaptured,
   isAudited,
   isAnalyzed,
+  isConsentChecked,
 } from "./brand-runtime";
 export { ConformanceError } from "./conformance-error";
 export { assertFeatureConformance } from "./assert-bindings";