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/channel-template.test.ts

@@ -0,0 +1,35 @@
+import { describe, it, expect } from "vitest";
+import { matchChannelTemplate } from "@/channel-template";
+
+describe("matchChannelTemplate", () => {
+  it("matches a plain channel name exactly", () => {
+    expect(matchChannelTemplate("blog.feed", "blog.feed")).toEqual({
+      params: {},
+    });
+    expect(matchChannelTemplate("blog.feed", "blog.other")).toBeNull();
+  });
+
+  it("matches a templated channel and extracts params", () => {
+    expect(
+      matchChannelTemplate(
+        "notifications.user.{userId}",
+        "notifications.user.user_42",
+      ),
+    ).toEqual({ params: { userId: "user_42" } });
+  });
+
+  it("returns null when a templated channel doesn't match the shape", () => {
+    expect(
+      matchChannelTemplate("notifications.user.{userId}", "notifications.user"),
+    ).toBeNull();
+    expect(
+      matchChannelTemplate("notifications.user.{userId}", "blog.feed"),
+    ).toBeNull();
+  });
+
+  it("supports multiple placeholders", () => {
+    expect(
+      matchChannelTemplate("rooms.{roomId}.user.{userId}", "rooms.r1.user.u1"),
+    ).toEqual({ params: { roomId: "r1", userId: "u1" } });
+  });
+});