Switch linter from semistandard to biome

Uses the recommended rules apart from complexity/useArrowFunction,
which would affect about 1700 lines of code with little benefit
right now. This is something that can be addressed over time.

docs/astro.config.mjs

@@ -1,6 +1,6 @@
 // @ts-check
-import { defineConfig } from 'astro/config';
 import starlight from '@astrojs/starlight';
+import { defineConfig } from 'astro/config';
 import starlightAutoSidebar from 'starlight-auto-sidebar';
 
 import { version } from '../package.json';

docs/build.mjs

@@ -1,8 +1,6 @@
 // Copyright 2013 Lovell Fuller and others.
 // SPDX-License-Identifier: Apache-2.0
 
-'use strict';
-
 import fs from 'node:fs/promises';
 import path from 'node:path';
 import jsdoc2md from 'jsdoc-to-markdown';