fix(ci): rename the cross-repo client — github-script already declares octokit

`actions/github-script` injects an `octokit` binding, so `const octokit = ...`
aborts the run with a SyntaxError before any logic executes. Caught on #4553's
own merge, the first time the workflow ever ran; until this lands every merged
PR carries one red check.

The pre-merge `node --check` missed it because the test wrapper declared only
{github, context, core, require} — a wrapper that omits an injected identifier
cannot see a collision with it. The wrapper now carries the full set.

Author: claude

.changeset/fix-cross-repo-closer-octokit.md

@@ -0,0 +1,23 @@
+---
+---
+
+fix(ci): rename the cross-repo client — `github-script` already declares `octokit`
+
+Release-nothing: touches `.github/workflows/cross-repo-issue-closer.yml` only.
+
+`actions/github-script` injects an `octokit` binding into the script scope, so
+the `const octokit = require('@actions/github').getOctokit(token)` added in
+#4553 aborted the run before a single line of logic executed:
+
+    SyntaxError: Identifier 'octokit' has already been declared
+
+This surfaced on #4553's own merge — the first time the workflow ever ran, and
+the first time any of its runtime behaviour was exercised. Until this lands,
+every merged pull request in this repository carries one red check.
+
+The pre-merge validation missed it for an instructive reason. The script was
+syntax-checked against a hand-written wrapper declaring `{github, context,
+core, require}` — and a wrapper that omits an injected identifier cannot
+possibly see a collision with it. The check reported clean because it was
+asking a narrower question than the runtime asks. The wrapper now carries the
+full injected set, and the previous spelling fails it.

.github/workflows/cross-repo-issue-closer.yml

@@ -103,25 +103,25 @@ jobs:
 
             // A second client: `github` is bound to GITHUB_TOKEN, which has no
             // write access outside this repository.
-            const octokit = require('@actions/github').getOctokit(token);
+            const crossRepo = require('@actions/github').getOctokit(token);
 
             for (const [key, t] of targets) {
               try {
-                const { data: issue } = await octokit.rest.issues.get({
+                const { data: issue } = await crossRepo.rest.issues.get({
                   owner: t.owner, repo: t.repo, issue_number: t.number,
                 });
                 if (issue.state === 'closed') {
                   core.info(`${key} is already closed — skipping.`);
                   continue;
                 }
-                await octokit.rest.issues.createComment({
+                await crossRepo.rest.issues.createComment({
                   owner: t.owner, repo: t.repo, issue_number: t.number,
                   body:
                     `已由 ${thisRepo} 的 ${prUrl} 修复并合并。\n\n` +
                     `（跨仓库的关闭关键字不会自动生效，本条由 \`cross-repo-issue-closer\` 工作流代为收口。）\n\n` +
                     `---\n_Generated by [Claude Code](https://claude.ai/code)_`,
                 });
-                await octokit.rest.issues.update({
+                await crossRepo.rest.issues.update({
                   owner: t.owner, repo: t.repo, issue_number: t.number,
                   state: 'closed', state_reason: 'completed',
                 });