feat: auto host mount dev server when running in a codespace

also clarify some documentation to consistently expect `pnpm` as a
package manager / task runner. `npm` _should_ work equivalently in
most cases, but being consistent might help prevent unexpected
surprises.

README.md

@@ -18,10 +18,7 @@ $ curl -s localhost:3141/refs/heads/master | jq '.version'
 ```bash
 # in packages/viewer
 # compile .js and .css assets
-npm run build
-
-# serve assets and expose them externally
-npm run start -- --host
+pnpm run dev
 ```
 
 ## Troubleshooting

packages/viewer/rollup.config.mjs

@@ -13,6 +13,7 @@ import copy from 'rollup-plugin-copy';
 import { spawn } from 'node:child_process';
 
 const production = !process.env.ROLLUP_WATCH;
+const codespace = process.env.CODESPACES === 'true';
 
 function serve() {
 	let server;
@@ -24,7 +25,10 @@ function serve() {
 	return {
 		writeBundle() {
 			if (server) return;
-			server = spawn('npm', ['run', 'start', '--', '--dev'], {
+			const args = ['run', 'start', '--', '--dev'];
+			if (codespace) { args.push('--host') }
+
+			server = spawn('pnpm', args, {
 				stdio: ['ignore', 'inherit', 'inherit'],
 				shell: true
 			});