feat(sat): the Satellites tab

Three questions answered at once, because on a pass there is no time to
go looking for any of them: where the bird is, when the next one comes,
and what to tune. The map draws each satellite's footprint — the honest
answer to "can I hear it", since everything inside the circle has the
satellite above its horizon — and the selected one's path over the
ground. The pass list is every favourite in time order, the one in
progress in green.

The readout shows the corrected frequency large and the nominal one
beneath it. Only one of them, and an operator cannot tell a Doppler
correction from a mistuned transponder.

The map opens on the station rather than the Atlantic, and remembers
where it was left like the others. The panel is mounted only while its
tab is visible: it asks for the tuning once a second, and there is no
reason to compute an orbit nobody is looking at.

changelog.json

@@ -1,4 +1,14 @@
 [
+  {
+    "version": "0.27.17",
+    "date": "",
+    "en": [
+      "[NEW] Satellites. A new tab (Tools → Satellites) tracks the amateur birds: a map with each satellite's footprint and the selected one's path over the ground, the next passes with their maximum elevation, and — for the satellite you are on — the azimuth, the elevation and the Doppler-corrected downlink and uplink. Orbital elements come from Celestrak (with a mirror behind it) and are kept on disk, so the tab is full the moment it opens even with no internet; elements for a bird no feed carries yet can be pasted in and survive every refresh. The shipped frequency list covers the FM and linear satellites and QO-100, and lives in a file you can correct yourself when a transponder is switched."
+    ],
+    "fr": [
+      "[NOUVEAU] Satellites. Un nouvel onglet (Outils → Satellites) suit les satellites amateurs : une carte avec l'empreinte de chacun et la trace au sol de celui qui est sélectionné, les prochains passages avec leur élévation maximale, et — pour le satellite en cours — l'azimut, l'élévation et les fréquences de descente et de montée corrigées de l'effet Doppler. Les éléments orbitaux viennent de Celestrak (avec un miroir derrière) et sont conservés sur disque : l'onglet est rempli dès son ouverture, même sans internet. Les éléments d'un satellite qu'aucun flux ne diffuse encore peuvent être collés à la main et survivent à chaque mise à jour. La liste de fréquences fournie couvre les satellites FM et linéaires ainsi que QO-100, dans un fichier que vous pouvez corriger vous-même quand un transpondeur change de mode."
+    ]
+  },
   {
     "version": "0.27.16",
     "date": "",