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/data/radio.test.mjs

@@ -1779,7 +1779,6 @@ test('voice playback confirmation waits for playing and requires a hard duck', a
 });
 
 test('voice playback confirmation accepts fallback buffering but times out safely', async () => {
-  let listener = () => {};
   const state = {
     audioState: 'loading',
     playingStationId: 'fallback',
@@ -1789,9 +1788,8 @@ test('voice playback confirmation accepts fallback buffering but times out safel
   const confirmed = await confirmRadioPlayback({
     startPlayback: async () => false,
     subscribe: (next) => {
-      listener = next;
       next(state);
-      return () => { listener = () => {}; };
+      return () => {};
     },
     getState: () => state,
     timeoutMs: 10,

src/data/trackedModelRegime.test.mjs

@@ -930,7 +930,6 @@ for (const fixture of LAYERS) {
 }
 
 test('both layers gate the tracked-model load and record its failures', async () => {
-  const { readFile } = await import('node:fs/promises');
   for (const name of ['flights.js', 'militaryFlights.js']) {
     const source = readLayerSource(new URL(`./${name}`, import.meta.url));
     assert.match(source, /!(?:flightState\.)?_trackedModel\s*&&\s*!(?:flightState\.)?_trackedModelLoading\s*&&\s*(?:parts\.\w+\.)?_trackedModelLoadAllowed\(\s*,?\s*\)/,
@@ -946,7 +945,6 @@ test('both layers gate the tracked-model load and record its failures', async ()
 });
 
 test('the tracked regime never consults the fleet models3d toggle', async () => {
-  const { readFile } = await import('node:fs/promises');
   for (const name of ['flights.js', 'militaryFlights.js']) {
     const source = readLayerSource(new URL(`./${name}`, import.meta.url));
     const regime = /^([ \t]*)function _trackedModelRegimeActive\b[\s\S]*?\n\1\}/m.exec(source)?.[0];