chore: remove the remaining unused local bindings

An ESLint no-unused-vars scan over src, server, scripts, tools, build
and pinokio, repeated until it is stable, reported these.

Runtime modules keep every call and drop only the unread binding:
- src/ui/cockpitInput.js: the unread result of enter()/exit().
- src/layers/launches/rendering.js: the unread entity returned by
  entities.add().
- src/layers/radio/rendering.js: the unread map key in the horizon scan,
  which now iterates the map's values.

QA scripts and tools drop an unused helper, two unused in-page module
imports, unused counters and destructured fields, and an unread wait
result. Tests drop source files read into variables that no assertion
uses, redundant StyleManager imports (the shell-source helper already
imports it), and unused destructured fields.

The one remaining report is the `_` loop variable in src/tools/schema.js,
which counts iterations and is intentional.

src/layers/transit/lifecycle.test.mjs

@@ -1406,7 +1406,6 @@ test('the selected card lands where the vehicle stopped, not short of it', async
   // segment ends left it a few metres behind, and then the render hold was
   // released with no frame scheduled to close the gap.
   const app = harness(t);
-  const start = Date.now();
   app.serve('mbta', () => ({
     status: 200,
     body: snapshot('mbta', 'MBTA', [vehicle('b', 42.36, -71.06, reported())], {