Factor EvalDescriptor out of SamplesDescriptor, improve JSDoc type annotations and more

src/inspect_ai/_view/www/.prettierrc.js

@@ -0,0 +1,12 @@
+// Do not remove this file even if the config is empty!
+// VSCode's "Format Document" will respect this config and use the default
+// settings, which is what we want. Without prettierrc, VSCode falls back to
+// users settings, which could be different.
+
+/**
+ * @see https://prettier.io/docs/en/configuration.html
+ * @type {import("prettier").Config}
+ */
+const config = {};
+
+export default config;