feat: migrate from Create React App to Vite

react-scripts 4 on React 17 no longer builds on a current toolchain.
Move to Vite 8 with React 19 and TypeScript 7, and take the same shape
as the other converted sites.

- react-router-dom v5 -> react-router v8: Switch/Redirect become
  Routes/Navigate, and withRouter gives way to useLocation and
  useNavigate; the original /modules/... addresses are kept
- swap the unmaintained dependencies: axios -> ky, react-html-parser
  -> @orrisroot/react-html-parser, react-ga -> react-ga4,
  react-helmet -> @dr.pogodin/react-helmet, moment -> date-fns,
  react-spinner-material -> a CSS spinner, and a local HashLink in
  place of react-router-hash-link
- drop react-app-polyfill, the jest setup, xregexp and the unused
  async-lock, rc-tree, react-overlays and react-image-lightbox
- replace ESLint with Biome, yarn with npm, and match the other sites'
  tsconfigs and sanitize.css base stylesheet
- serve static-contents/ next to the repository with sirv in the dev
  and preview servers, keeping it out of dist/
- convert the page components to function components; each module
  loads its index once, sharing the request under StrictMode
- resolve relative links in page bodies the way a browser does, since
  react-router 8 resolves them against the route hierarchy
- fix the glossary search restricted to a category, whose query
  matched nothing
- set the GA4 measurement ID replacing the shut-down UA property
- correct the keywords meta tag copied from dynamicbrain
- write down the data layout and the deployment procedure

src/common/lib/Loading.module.css

@@ -0,0 +1,27 @@
+.container {
+    display: flex;
+    justify-content: center;
+    align-content: center;
+    margin: 100px 0;
+}
+
+.spinner {
+    width: 120px;
+    height: 120px;
+    border: 8px solid #eeeeee;
+    border-top-color: #cccccc;
+    border-radius: 50%;
+    animation: spin 1s linear infinite;
+}
+
+@keyframes spin {
+    to {
+        transform: rotate(360deg);
+    }
+}
+
+@media (prefers-reduced-motion: reduce) {
+    .spinner {
+        animation-duration: 4s;
+    }
+}