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/consent.interface.ts

@@ -0,0 +1,22 @@
+import type { ConsentCategory, UserConsentState } from "./consent-types";
+
+/**
+ * Vendor-neutral consent management interface.
+ *
+ * Feature binders that receive a consent instance operate through this
+ * interface. Concrete implementations (Payload-backed, in-memory, etc.) are
+ * wired at DI bind time and never imported by feature packages directly.
+ */
+export interface IConsent {
+  /** Synchronous check — true when the subject has granted the category. */
+  isGranted(category: ConsentCategory): boolean;
+
+  /** Record a consent grant for the given category. */
+  grant(category: ConsentCategory): Promise<void>;
+
+  /** Record a consent withdrawal for the given category. */
+  withdraw(category: ConsentCategory): Promise<void>;
+
+  /** Return the full list of per-category consent states. */
+  getCategories(): UserConsentState[];
+}