feat(conformance): wire cross-feature reader pattern into docs and schema

Add reads field to UseCaseManifest, update CLAUDE.md with Q0-Q3 rules,
add ./reader subpath to AGENTS.md exports table, and cascade reader
conventions through conformance quickref, adding-a-feature guide, and
scaffolding guide. Moves gen reader from deferred to planned.

packages/core-shared/src/conformance/define-feature.ts

@@ -4,14 +4,17 @@ import type { RateLimitBudget } from "../rate-limit/rate-limit.interface";
 /**
  * Per-use-case manifest entry. Declares what the use case does at the contract
  * level: whether it mutates state, what audit events it emits, what cross-feature
- * events it publishes or consumes. The conformance system reads these to
- * derive binding-slot types and to verify code against manifest declarations.
+ * events it publishes or consumes, and what cross-feature readers it depends on.
+ * The conformance system reads these to derive binding-slot types and to verify
+ * code against manifest declarations.
  */
 export type UseCaseManifest = {
   readonly mutates: boolean;
   readonly audits: readonly string[];
   readonly publishes: readonly string[];
   readonly consumes: readonly string[];
+  /** Feature names whose readers this use case queries. */
+  readonly reads?: readonly string[];
   readonly analyticsEvents?: readonly string[];
   readonly rateLimit?: readonly RateLimitBudget[];
 };