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-consent/src/index.ts

@@ -0,0 +1,8 @@
+export type {
+  ConsentCategory,
+  ConsentState,
+  UserConsentState,
+} from "./consent-types";
+export type { IConsent } from "./consent.interface";
+export type { ConsentChecked } from "./with-consent";
+export { withConsent } from "./with-consent";