Declare logger, refresh action pins, drop grunt tooling

[amjjbonvin]

Backlog items 5, 6 and 7.

Item 5 — declare logger

Jekyll 4.4 requires logger but does not declare it, so it resolved from the
standard library and warned on every build. Ruby 3.5 removes it from the default
gems, at which point a bundled build without it is expected to fail rather than
warn.

Declared as gem "logger", "~> 1.6" → resolves to 1.7.0. Warning is gone.

Item 6 — refresh action pins

Action	Was	Now
actions/checkout	v4	v7
actions/cache	v4	v6
actions/configure-pages	v4	v6
actions/deploy-pages	v4	v5
actions/upload-pages-artifact	v3	v5

checkout@v4 was the source of the Node 20 deprecation annotation on every run.

I checked the release notes before bumping: no breaking changes — the majors are
Node runtime upgrades and internal dependency bumps. upload-pages-artifact v5
uses upload-artifact v7 internally and deploy-pages v5 is its matching
generation, so the trio moves together. lychee-action and ruby/setup-ruby were
already current on their floating major tags.

Item 7 — drop the grunt tooling

Deleted package.json, Gruntfile.js, .jshintrc, plus the now-stale
Gruntfile.js / package.json entries in the _config.yml exclude list.

Nothing referenced them — no workflow, script or page, no package-lock.json, no
node_modules. assets/js/scripts.min.js is committed, so no build output is
lost.

This permanently closes the phantom grunt Dependabot alerts. The pin in
6e817a9 only raised the declared range; with the manifest gone there is nothing
left to scan, so the seven grunt-* dependencies still on open-ended ">1.3.0"
ranges cannot raise alerts either.

Worth noting the theme this tooling belonged to was already gone twice over:
#789 removed theme: minima, and package.json had long claimed to be
minimal-mistakes-theme — a third theme the site had not used in years.

Verification

• Built site is byte-identical to the previous baseline across all 1242 files
• logger warning no longer appears
• Only the @import Sass deprecation remains, deferred by design (see Clear three of four Sass deprecation categories #789)

One thing a PR cannot verify

The deploy workflow only runs on push to master, so this PR does not exercise
the upgraded Pages actions. build.yml covers checkout@v7 and the Jekyll
build, but configure-pages@v6 / upload-pages-artifact@v5 / deploy-pages@v5
run for the first time on merge. They are a coordinated set with no documented
breaking changes, so the risk is low — but worth watching the deploy run, and the
live site, immediately after merging.

🤖 Generated with Claude Code