chore(core-events): scaffold package

Create @repo/core-events package skeleton with package.json, tsconfig.json,
vitest.config.ts (using mergeConfig with nodeVitestConfig), eslint.config.js,
turbo.json (tagged core), and AGENTS.md. Register workspace via pnpm install.

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

pnpm-lock.yaml

@@ -516,6 +516,31 @@ importers:
         specifier: ^8.25.0
         version: 8.58.0(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
 
+  packages/core-events:
+    dependencies:
+      '@repo/core-shared':
+        specifier: workspace:*
+        version: link:../core-shared
+      payload:
+        specifier: ^3.0.0
+        version: 3.81.0(graphql@16.13.2)(typescript@5.9.3)
+      zod:
+        specifier: ^3.23.0
+        version: 3.25.76
+    devDependencies:
+      '@repo/core-eslint':
+        specifier: workspace:*
+        version: link:../core-eslint
+      '@repo/core-typescript':
+        specifier: workspace:*
+        version: link:../core-typescript
+      typescript:
+        specifier: ^5.8.0
+        version: 5.9.3
+      vitest:
+        specifier: ^3.0.0
+        version: 3.2.4(@types/debug@4.1.13)(@types/node@25.5.2)(happy-dom@20.8.9)(jiti@2.6.1)(jsdom@25.0.1)(lightningcss@1.32.0)(sass@1.99.0)(terser@5.46.2)(tsx@4.21.0)
+
   packages/core-shared:
     dependencies:
       '@sentry/nextjs':