add checkout:pr npm script and update documentation usage

CONTRIBUTING.md

@@ -58,7 +58,7 @@ Current Reviewers:
 To quickly check out a PR branch from a fork for local testing, see the [Testing a fork branch](DEVELOPMENT.md#testing-a-fork-branch) section in `DEVELOPMENT.md`, or run:
 
 ```sh
-node scripts/checkout-pr.js https://github.com/meteor/meteor/pull/<PR-number>
+npm run checkout:pr -- https://github.com/meteor/meteor/pull/<PR-number>
 ```
 
 #### Core Committer

DEVELOPMENT.md

@@ -70,13 +70,13 @@ When reviewing a pull request or testing changes from a contributor's fork, use
 
 ```sh
 # From a PR URL (requires gh CLI or falls back to GitHub API via curl)
-$ node scripts/checkout-pr.js https://github.com/meteor/meteor/pull/<PR-number>
+$ npm run checkout:pr -- https://github.com/meteor/meteor/pull/<PR-number>
 
 # From a user:branch shorthand
-$ node scripts/checkout-pr.js <user>:<branch>
+$ npm run checkout:pr -- <user>:<branch>
 
-# From a full fork repo URL and branch name
-$ node scripts/checkout-pr.js <fork-repo-url> <branch>
+# From a full fork repo URL and branch name (HTTPS or SSH)
+$ npm run checkout:pr -- <fork-repo-url> <branch>
 ```
 
 The script will:

package.json

@@ -39,7 +39,8 @@
     "test:unit": "cd tools/unit-tests && npm test",
     "test:idle-bot": "node --test .github/scripts/__tests__/inactive-issues.test.js",
     "install:e2e": "cd tools/modern-tests && npm install && npx playwright install --with-deps chromium chromium-headless-shell",
-    "test:e2e": "cd tools/modern-tests && npm test -- "
+    "test:e2e": "cd tools/modern-tests && npm test -- ",
+    "checkout:pr": "node scripts/checkout-pr.js"
   },
   "jshintConfig": {
     "esversion": 11