chore(js): polish pong keys, held mapping and m09 main test

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

js/test/helpers.js

@@ -1,6 +1,9 @@
 import { readFileSync } from 'node:fs'
 import { fileURLToPath } from 'node:url'
 import { dirname, join } from 'node:path'
+import { states, classicActions, render } from '../src/app.js'
+import { map as mapStream } from '../src/stream.js'
+import { map as mapIO, randomSeed } from '../src/io.js'
 
 const here = dirname(fileURLToPath(import.meta.url))
 
@@ -17,3 +20,6 @@ export const freeze = (x, seen = new WeakSet()) => {
   }
   return x
 }
+
+/** The m09 program built from classicActions (ticks every 150 ms). The shipped `main` switches to speedActions in m10. */
+export const classicMain = mapIO(randomSeed, (seed) => mapStream(states(seed, classicActions), render))