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/creditAttribution.test.mjs

@@ -1,4 +1,3 @@
-import { readShellSource } from './testSupport/readShellSource.mjs';
 import { readStylesheet } from './testSupport/readStylesheet.mjs';
 import assert from 'node:assert/strict';
 import fs from 'node:fs';
@@ -8,7 +7,6 @@ import { fileURLToPath } from 'node:url';
 
 const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
 const css = readStylesheet(path.join(ROOT, 'style.css'));
-const ui = readShellSource();
 
 /*
  * Required-attribution keep-out pin.