Read a satellite's launch year from one TLE parser

The catalog stored the designator on satrec.intldesg for
internationalDesignatorYear, while the active-TLE lookup parsed the same
columns with tleLineLaunchYear. Each catalog entry now keeps launchYear from
tleLineLaunchYear, which moves to src/sources/tle.js beside the other TLE
field readers, and internationalDesignatorYear goes.

A blank designator now reads as an unknown year in both lookups; the
active-TLE lookup read it as 2000.

src/layers/satellites/catalog.js

@@ -1,6 +1,6 @@
 import * as Cesium from 'cesium';
 import { twoline2satrec } from 'satellite.js';
-import { noradIdFromSatnum } from '../../sources/tle.js';
+import { noradIdFromSatnum, tleLineLaunchYear } from '../../sources/tle.js';
 import {
   DENSE_REFRESH_FRAMES,
   DENSE_GROUP_PATH,
@@ -114,8 +114,6 @@ export function createCatalog({ state: layerState, services, parts, source }) {
           const entry = entries[i];
           const satrec = twoline2satrec(entry.line1, entry.line2);
           if (!satrec || satrec.error !== 0) continue;
-          // satellite.js omits the designator the launch-year match reads.
-          satrec.intldesg = entry.line1.slice(9, 17).trim();
           const noradId = noradIdFromSatnum(satrec.satnum);
           if (layerState._catalog.has(noradId)) continue; // core catalog keeps priority
           const pos = parts.orbits.propagatePosition(satrec, now);
@@ -125,6 +123,7 @@ export function createCatalog({ state: layerState, services, parts, source }) {
             name: entry.name,
             satrec,
             group: 'dense',
+            launchYear: tleLineLaunchYear(entry.line1),
           });
           const point = layerState._pointCollection.add({
             position: Cesium.Cartesian3.fromDegrees(