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.

docs/guides/scaffolding-a-feature.md

@@ -111,6 +111,7 @@ pnpm turbo gen event consume     # consumer handler + Payload event-task
 pnpm turbo gen job               # background job + TaskConfig
 pnpm turbo gen realtime channel  # realtime channel descriptor (ADR-016)
 pnpm turbo gen realtime handler  # inbound realtime handler (ADR-016)
+pnpm turbo gen reader            # cross-feature reader interface + implementation
 ```
 
 The event/job generators insert at six fixed `// <gen:*>` anchor comments. Generated features include four of them automatically (the `// <gen:job-tasks>` location is in `integrations/cms/index.ts`, which is manually authored as part of the post-scaffold wiring); pre-existing features were retrofitted in ADR-015.
@@ -127,4 +128,5 @@ The realtime generators insert at three additional fixed `// <gen:realtime-*>` a
 - `docs/decisions/adr-013-input-output-unification.md` — schemas-in-use-case + presenter
 - `docs/decisions/adr-014-instrumentation-sentry.md` — span + capture wiring
 - `docs/decisions/adr-015-events-and-jobs.md` — cross-feature events + background jobs
+- `docs/decisions/adr-026-cross-feature-readers.md` — cross-feature synchronous readers
 - `docs/decisions/adr-016-realtime-layer.md` — Socket.IO realtime channels + handlers