chore: Fix unit tests broken by @actions/github v8 upgrade

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

__mocks__/@actions/github.js

@@ -0,0 +1,49 @@
+'use strict';
+
+// CJS shim for @actions/github (v9+ is ESM-only, incompatible with Jest's CJS resolver).
+// Replicates the Context class behaviour used by this repo: reads GITHUB_* env vars.
+const context = {
+  get repo() {
+    const [owner, repo] = (process.env['GITHUB_REPOSITORY'] || '/').split('/');
+    return {owner, repo};
+  },
+  get eventName() {
+    return process.env['GITHUB_EVENT_NAME'] || '';
+  },
+  get sha() {
+    return process.env['GITHUB_SHA'] || '';
+  },
+  get ref() {
+    return process.env['GITHUB_REF'] || '';
+  },
+  get workflow() {
+    return process.env['GITHUB_WORKFLOW'] || '';
+  },
+  get action() {
+    return process.env['GITHUB_ACTION'] || '';
+  },
+  get actor() {
+    return process.env['GITHUB_ACTOR'] || '';
+  },
+  get job() {
+    return process.env['GITHUB_JOB'] || '';
+  },
+  get runNumber() {
+    return parseInt(process.env['GITHUB_RUN_NUMBER'] || '0', 10);
+  },
+  get runId() {
+    return parseInt(process.env['GITHUB_RUN_ID'] || '0', 10);
+  },
+  get apiUrl() {
+    return process.env['GITHUB_API_URL'] || 'https://api.github.com';
+  },
+  get serverUrl() {
+    return process.env['GITHUB_SERVER_URL'] || 'https://github.com';
+  },
+  get graphqlUrl() {
+    return process.env['GITHUB_GRAPHQL_URL'] || 'https://api.github.com/graphql';
+  },
+  payload: {}
+};
+
+module.exports = {context};

jest.config.js

@@ -7,5 +7,8 @@ module.exports = {
   transform: {
     '^.+\\.ts$': 'ts-jest'
   },
-  verbose: true
+  verbose: true,
+  moduleNameMapper: {
+    '^@actions/github$': '<rootDir>/__mocks__/@actions/github.js'
+  }
 }