Remove .html from internal links

scripts/copy-static-assets.mjs

@@ -11,6 +11,36 @@ function copyDir(source, destination) {
   fs.cpSync(source, destination, { recursive: true });
 }
 
+function listHtmlFiles(dir) {
+  return fs.readdirSync(dir, { withFileTypes: true }).flatMap((entry) => {
+    const fullPath = path.join(dir, entry.name);
+    if (entry.isDirectory()) {
+      return listHtmlFiles(fullPath);
+    }
+    return entry.isFile() && entry.name.endsWith(".html") ? [fullPath] : [];
+  });
+}
+
+function materializeExtensionlessHtmlRoutes() {
+  let routes = 0;
+
+  for (const filePath of listHtmlFiles(distRoot)) {
+    const relativePath = path.relative(distRoot, filePath);
+    const extensionlessPath = relativePath.replace(/\.html$/, "");
+    const destination = path.join(distRoot, extensionlessPath, "index.html");
+
+    if (path.resolve(destination) === path.resolve(filePath)) {
+      continue;
+    }
+
+    fs.mkdirSync(path.dirname(destination), { recursive: true });
+    fs.copyFileSync(filePath, destination);
+    routes += 1;
+  }
+
+  return routes;
+}
+
 for (const dir of staticDirs) {
   copyDir(path.join(repoRoot, dir), path.join(distRoot, dir));
 }
@@ -30,4 +60,7 @@ if (fs.existsSync(adminIndexSource)) {
   fs.copyFileSync(adminIndexSource, adminIndexDestination);
 }
 
+const extensionlessRoutes = materializeExtensionlessHtmlRoutes();
+
 console.log(`Copied ${staticDirs.join(", ")} into dist/.`);
+console.log(`Materialized ${extensionlessRoutes} extensionless HTML route aliases.`);