chore: drop exports nothing imports

Knip, configured with the application, package exports, scripts, QA
harnesses, workers, tools and tests as entry points, reports exports
that no module imports. Each was checked by hand against string-based
and namespace imports.

- Symbols that are still used inside their own module lose only the
  `export` keyword (176 constants and helpers).
- Unused re-exports are removed from barrel modules (flight, military,
  vessel, CCTV, directions, transit history, local ADS-B and street-level
  policy modules).
- Declarations that nothing uses at all are deleted, among them
  AIS_WATCHDOG_STATUSES, applyFilter, isRadioCountryCode, compactText,
  DENSITY_STOPS, the unused CCTV endpoint constants, and the SDR band
  constants.
- Default exports that nothing imports are removed. The ones in
  src/data/earthquakes.js, src/data/telegeographySubmarineCables.js,
  src/data/wind.js and src/data/bhoteKoshiLocator.js each constructed a
  layer instance at import time that nothing used; those instances are
  no longer created.

Every export of a package.json entry stays, as does TOMTOM_CREDIT,
which the traffic layer reads from the credits namespace it is given.

src/tools/queries/panelRequest.js

@@ -55,7 +55,7 @@ const COMPRESS_MIN_BYTES = 1024;
  * rather than fail; past `PANEL_QUEUED_REQUESTS` waiting, they are refused.
  */
 export const PANEL_CONCURRENT_REQUESTS = 6;
-export const PANEL_QUEUED_REQUESTS = 256;
+const PANEL_QUEUED_REQUESTS = 256;
 
 /**
  * Each server's panel state: bodies too large for one call, kept for the

src/tools/queries/share.js

@@ -7,7 +7,7 @@ import { AREA_SCHEMA, resolveArea } from '../area.js';
 import { cameraForArea, cameraLookingAt } from '../views.js';
 
 /** Tool arguments that describe a view: an area to frame, or a camera. */
-export const VIEW_ARGUMENTS = Object.freeze({
+const VIEW_ARGUMENTS = Object.freeze({
   view: Object.freeze({
     type: 'object',
     description: