Bump link-cache to 0.6.0 and migrate the cache to link-cache.jsonc

.github/workflows/links.yaml

@@ -57,7 +57,7 @@ jobs:
           npm run -s _is:clean || {
             echo
             echo 'ERROR: generated files changed; regenerate locally and commit:'
-            echo '  .lycheecache               -> npm run check:links'
+            echo '  link-cache.jsonc           -> npm run fix:link-cache'
             echo '  package-lock, hugoautogen  -> npm run update:docsy:pack'
             echo
             exit 1

.gitignore

@@ -4,3 +4,6 @@ resources/
 node_modules/
 .hugo_build.lock
 packages/hugoautogen/hugo_packagemeta.json
+
+# Lychee link-check cache: derived from link-cache.jsonc by lychee-norm-cache
+.lycheecache

CONTRIBUTING.md

@@ -114,13 +114,27 @@ npm run local -- serve
 The `local` prefix runs the script against the sibling Docsy, and the server
 watches it, so theme edits hot-reload.
 
+### Link checking
+
+For the link cache (the committed `link-cache.jsonc`, its fields, and the
+refresh, prune, and seed recipes), see Docsy's [Link checking and the link
+cache][]. What differs here:
+
+- The cache and `lychee.toml` are at the repo root, and CI runs the check in
+  `.github/workflows/links.yaml`.
+- No refresh workflow: a lapsed seed keeps serving until you prune by hand. Run
+  `npm run link-cache -- -p 0` (drops only lapsed entries; `-p N` also drops the
+  N oldest without `expires`), then `npm run fix:link-cache` to re-verify those
+  URLs, and commit the cache.
+
 <!-- prettier-ignore-start -->
 [alternate dashboard]: https://app.netlify.com/sites/goldydocs/deploys
 [contribution guidelines]: https://main--docsydocs.netlify.app/docs/contributing/
 [Dependency updates]: https://main--docsydocs.netlify.app/project/about/maintainer-notes/#dependency-updates
 [deploys]: https://app.netlify.com/sites/docsy-example/deploys
 [Docsy]: https://github.com/docsy/docsy
 [Hugo workspace]: https://gohugo.io/configuration/module/#top-level-settings
+[Link checking and the link cache]: https://main--docsydocs.netlify.app/project/about/maintainer-notes/#link-checking-and-the-link-cache
 [Lockfile and generated manifest]: #lockfile-and-generated-manifest
 [main ruleset]: https://github.com/docsy/docsy-example/rules/23697395
 [Merge requirements]: https://main--docsydocs.netlify.app/project/about/maintainer-notes/#merge-requirements