fix: address Phase 1 spec review findings

- di-explainer.html: update stale JS data strings from positional-arg
  form (bindAllProduction(config), bindProductionBlog(config,tracer,...))
  to ctx-arg form (bindAllProduction(deps), bindProductionBlog(ctx)) with
  a note on ctx shape.
- auth/sign-up.use-case: change bus param from IEventBus to
  EventBusProtocol|undefined; guard bus.publish with if(bus) so the use
  case is safe when core-events is absent (Phase 3+).
- auth/bind-production + bind-dev-seed: drop as IEventBus cast and unused
  IEventBus import; ctx.bus is now passed directly (typed as
  EventBusProtocol|undefined).
- marketing-pages/bind-production + bind-dev-seed: drop as IJobQueue cast
  and unused IJobQueue import; wrap event-handler DI block in if(queue)
  guard so the handler is only bound when core-jobs is wired.
- core-shared/src/index.ts: add `export * from "./di"` as the plan
  specified (subpath export alone is no longer the only access path).

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

packages/auth/src/application/use-cases/sign-up.use-case.ts

@@ -1,6 +1,6 @@
 import { z } from "zod";
 
-import type { IEventBus } from "@repo/core-events";
+import type { EventBusProtocol } from "@repo/core-shared/di";
 import { userSignedUpEvent } from "../../events/user-signed-up.event";
 import { AuthenticationError } from "../../entities/errors/auth";
 import { cookieSchema } from "../../entities/models/cookie";
@@ -36,7 +36,7 @@ export const signUpUseCase =
   (
     usersRepository: IUsersRepository,
     authenticationService: IAuthenticationService,
-    bus: IEventBus,
+    bus: EventBusProtocol | undefined,
   ) =>
   async (input: SignUpInput): Promise<SignUpOutput> => {
     const existingUser = await usersRepository.getUserByUsername(input.username);
@@ -57,11 +57,14 @@ export const signUpUseCase =
 
     // Auth is username-based — synthesize a deterministic email so the event
     // payload validates against userSignedUpEventSchema.email().
-    await bus.publish(userSignedUpEvent, {
-      userId: newUser.id,
-      email: `${newUser.username}@example.local`,
-      signedUpAt: new Date().toISOString(),
-    });
+    // bus is optional: absent when core-events is not wired (Phase 3+).
+    if (bus) {
+      await bus.publish(userSignedUpEvent, {
+        userId: newUser.id,
+        email: `${newUser.username}@example.local`,
+        signedUpAt: new Date().toISOString(),
+      });
+    }
 
     return signUpOutputSchema.parse({ session, cookie });
   };