feat(core-realtime): scaffold realtime optional core

Generator-emitted scaffold (pnpm turbo gen core-package realtime) plus
the story-00-precedent coverage repairs (coverage provider devDep,
symbols.ts exclude + tested allowlist mirror) and three minimal tests
covering generator-emitted realtime code the template suite misses.
Squash of 31d85e0 + review-fix cf11b38.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016j8z4VHjedXDTjEDNg7qHK

packages/core-realtime/src/realtime-handler-registry.ts

@@ -0,0 +1,57 @@
+import type { z } from "zod";
+import type { RealtimeRegistryProtocol } from "@repo/core-shared/di/bind-protocols";
+import type { RealtimeChannelDescriptor } from "./realtime-channel";
+import type { IInboundDescriptor } from "./realtime-handler.interface";
+
+export interface IRealtimeHandlerRegistry extends RealtimeRegistryProtocol {
+  register<T>(entry: IInboundDescriptor<string, z.ZodType<T>>): void;
+  getInboundDescriptor(
+    channelName: string,
+  ): IInboundDescriptor<string, z.ZodType> | null;
+  list(): IInboundDescriptor<string, z.ZodType>[];
+  /** Register an outbound-only channel so Gate 2 can authorize subscriptions to it. */
+  registerChannel(
+    descriptor: RealtimeChannelDescriptor<string, z.ZodType>,
+  ): void;
+  listChannels(): RealtimeChannelDescriptor<string, z.ZodType>[];
+}
+
+export class RealtimeHandlerRegistry implements IRealtimeHandlerRegistry {
+  private readonly entries = new Map<
+    string,
+    IInboundDescriptor<string, z.ZodType>
+  >();
+  private readonly channels = new Map<
+    string,
+    RealtimeChannelDescriptor<string, z.ZodType>
+  >();
+
+  register<T>(entry: IInboundDescriptor<string, z.ZodType<T>>): void {
+    this.entries.set(
+      entry.descriptor.name,
+      entry as IInboundDescriptor<string, z.ZodType>,
+    );
+    // Also add the descriptor to the channel map so Gate 2 can authorize subscriptions.
+    this.channels.set(entry.descriptor.name, entry.descriptor);
+  }
+
+  getInboundDescriptor(
+    channelName: string,
+  ): IInboundDescriptor<string, z.ZodType> | null {
+    return this.entries.get(channelName) ?? null;
+  }
+
+  list(): IInboundDescriptor<string, z.ZodType>[] {
+    return Array.from(this.entries.values());
+  }
+
+  registerChannel(
+    descriptor: RealtimeChannelDescriptor<string, z.ZodType>,
+  ): void {
+    this.channels.set(descriptor.name, descriptor);
+  }
+
+  listChannels(): RealtimeChannelDescriptor<string, z.ZodType>[] {
+    return Array.from(this.channels.values());
+  }
+}