Add retry logic for transient HTTP errors in markdown link checker (#1899)

* Add retry logic for transient HTTP errors in markdown link checker

Configure markdown-link-check to retry on transient server errors (500, 502, 503, 504)
in addition to rate limit errors (429). This prevents CI failures from flaky external
links that temporarily return 502 Bad Gateway or similar intermittent errors.

Changes:
- Increase retryCount from 3 to 5 for better resilience
- Add explicit retry configuration with 10-second delays between attempts
- Configure retries for HTTP status codes: 429, 500, 502, 503, 504

This should resolve the flaky test failures where external links like
https://github.com/shakacode/react_on_rails_demo_ssr_hmr occasionally return 502 errors.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

* Fix markdown link checker to properly retry on transient errors

The previous commit added an invalid 'retry' configuration object that is not
supported by markdown-link-check, which only retries on HTTP 429 (rate limiting).

This commit implements proper retry logic by:
1. Wrapping the markdown-link-check action with Wandalen/wretry.action
2. Configuring 3 retry attempts with 10-second delays between attempts
3. Removing the unsupported 'retry' configuration object from the JSON config
4. Increasing retryCount to 5 for 429 rate limit handling

This approach will retry the entire link check operation when it fails due to
transient errors like 502 Bad Gateway, while maintaining the existing 429
retry configuration for rate limiting.

Impact on CI time: Each retry adds ~10 seconds, so worst case is +20 seconds
for a completely failing run (which would fail anyway without retries).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

---------

Co-authored-by: Claude <[email protected]>

Author: justin808

.github/markdown-link-check-config.json

@@ -41,7 +41,7 @@
   ],
   "timeout": "20s",
   "retryOn429": true,
-  "retryCount": 3,
+  "retryCount": 5,
   "fallbackRetryDelay": "30s",
   "aliveStatusCodes": [200, 206]
 }

.github/workflows/check-markdown-links.yml

@@ -23,14 +23,18 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Check markdown links
-        uses: tcort/github-action-markdown-link-check@a800ad5f1c35bf61987946fd31c15726a1c9f2ba # v1.1.0
+      - name: Check markdown links (with retry on transient errors)
+        uses: Wandalen/wretry.action@v3.5.0
         with:
-          use-quiet-mode: 'yes'
-          use-verbose-mode: 'no'
-          config-file: '.github/markdown-link-check-config.json'
-          folder-path: 'docs/'
-          file-extension: '.md'
-          max-depth: -1
-          check-modified-files-only: 'no'
-          base-branch: 'master'
+          action: tcort/github-action-markdown-link-check@a800ad5f1c35bf61987946fd31c15726a1c9f2ba
+          with: |
+            use-quiet-mode: yes
+            use-verbose-mode: no
+            config-file: .github/markdown-link-check-config.json
+            folder-path: docs/
+            file-extension: .md
+            max-depth: -1
+            check-modified-files-only: no
+            base-branch: master
+          attempt_limit: 3
+          attempt_delay: 10000