Commit the Alpine.js tarball in 3p/ and extract it at build time (closes #345)

The build no longer downloads Alpine.js. Its npm package tarball is committed as 3p/alpinejs-3.14.9.tgz, byte for byte the file script/fetch-assets downloaded, with the sha256 that script pinned. script/assets (make assets) extracts package/dist/cdn.min.js to the ignored static/js/alpine.min.js; script/test runs it, so make test, make check, the pre-commit hook and the Dockerfile get the file with no network access, and make build, run and dev run it too.

Removed: script/fetch-assets, its Dockerfile step, static/vendor.sha256 and static/vendor_test.go. The README describes the new flow.

Model: opus-5-5

internal/server/static_assets_test.go

@@ -13,9 +13,9 @@ import (
 
 // TestBaseTemplateScriptsAreServed walks every /s/ script the base
 // template loads on each page and fetches it through the real router.
-// Alpine.js is fetched at build time rather than committed, so nothing
-// in the repo guarantees it is present: this is the check that the page
-// still gets the JavaScript it asks for.
+// Alpine.js is extracted from its tarball in 3p/ at build time, so the
+// file is not in the tree: this is the check that the page still gets
+// the JavaScript it asks for.
 func TestBaseTemplateScriptsAreServed(t *testing.T) {
 	t.Parallel()