feat(antenna): three tracking modes for Ultrabeam and SteppIR

The follow loop only ever had one behaviour — re-tune once the rig moved
further than a fixed step. The SteppIR's own controller software offers three,
and operators arrive with that mental model: every frequency change, past a
threshold, or only on a band change. They are real operating trade-offs, not
preferences: "always" keeps resonance perfect at the cost of motors running
constantly (and on a SteppIR every move inhibits transmit while the elements
travel), "band" moves them a handful of times a day.

"Always" is implemented as the threshold mode with a 1 kHz threshold rather
than as a separate branch, so all modes keep the one deadband reference that
matters: the rig frequency last commanded for, NOT the antenna's own reported
frequency — a SteppIR flips its reported frequency between the commanded value
and its home value, which would re-issue a SET on nearly every poll and leave
the operator permanently unable to transmit.

Band mode compares against the band last COMMANDED for, not the rig's previous
band, so the first move after startup and any move made by hand still get
reconciled. It applies to the immediate spot-click path too: a click inside the
band the antenna is already resonant in moves nothing.

An unset or unrecognised mode resolves to the step mode, so every config
written before this option behaves exactly as it did.

Also routes the antenna settings block through t() — it was hardcoded English.

changelog.json

@@ -6,13 +6,15 @@
       "QSOs logged from WSJT-X now carry the space weather and the distance, like hand-logged ones. The UDP path stamped the station profile, the DXCC and the QSL defaults but not SFI, A, K or distance — so an operator running digital had those fields empty across the whole log. Space weather is only stamped on a contact less than a day old: a logger re-broadcasting its backlog would otherwise be handed this morning readings for last month contacts.",
       "Band openings: EME contacts are no longer mistaken for an opening. A 2 m opening was announced at 9650 km towards Japan on stations working moonbounce — real contacts, but the moon says nothing about the band, and an antenna pointed that way finds nothing. Each band now has the longest path the atmosphere can actually carry: 3500 km on 2 m, 4000 on 4 m, and no limit at all on 6 and 10 m where multi-hop really does go round the world.",
       "Kenwood: WSJT-X \"Fake It\" no longer leaves the dial on the transmit frequency. A frequency set while transmitting was not recorded, so WSJT-X was told the radio was already back on the receive frequency and never restored it.",
-      "PowerGenius XL: the Station Control card now shows power, current, SWR and temperature without a FlexRadio. The meters were only ever drawn from the radio's stream, so a station on any other rig got an empty card while the amplifier was reporting all four over its own link."
+      "PowerGenius XL: the Station Control card now shows power, current, SWR and temperature without a FlexRadio. The meters were only ever drawn from the radio's stream, so a station on any other rig got an empty card while the amplifier was reporting all four over its own link.",
+      "Motorized antennas (Ultrabeam and SteppIR): tracking now offers the three modes the SteppIR controller software has — every frequency change, past a step of 25/50/100 kHz, or only when the band changes. Existing setups keep the step mode they already had."
     ],
     "fr": [
       "Les QSO enregistrés depuis WSJT-X portent désormais la météo spatiale et la distance, comme ceux saisis à la main. Le chemin UDP posait le profil station, le DXCC et les défauts QSL mais ni SFI, ni A, ni K, ni distance — un opérateur en numérique avait donc ces champs vides sur tout son log. La météo spatiale n est posée que sur un contact de moins d un jour : sinon un logiciel qui rediffuse son historique se verrait attribuer les relevés de ce matin sur des contacts du mois dernier.",
       "Ouvertures de bande : les contacts EME ne sont plus pris pour une ouverture. Une ouverture 2 m était annoncée à 9650 km vers le Japon sur des stations en rebond lunaire — de vrais contacts, mais la Lune ne dit rien de la bande, et une antenne pointée par là ne trouve rien. Chaque bande a désormais la distance maximale que l atmosphère peut réellement porter : 3500 km en 2 m, 4000 en 4 m, et aucune limite en 6 et 10 m où les sauts multiples font vraiment le tour du monde.",
       "Kenwood : le « Fake It » de WSJT-X ne laisse plus le VFO sur la fréquence d émission. Un changement de fréquence pendant l émission n était pas enregistré, WSJT-X croyait donc la radio déjà revenue sur la fréquence de réception et ne la remettait jamais en place.",
-      "PowerGenius XL : la carte du Contrôle station affiche désormais puissance, courant, ROS et température sans FlexRadio. Les mesures n étaient tirées que du flux de la radio, si bien qu une station sur une autre radio n avait qu une carte vide alors que l amplificateur remontait les quatre sur sa propre liaison."
+      "PowerGenius XL : la carte du Contrôle station affiche désormais puissance, courant, ROS et température sans FlexRadio. Les mesures n étaient tirées que du flux de la radio, si bien qu une station sur une autre radio n avait qu une carte vide alors que l amplificateur remontait les quatre sur sa propre liaison.",
+      "Antennes motorisées (Ultrabeam et SteppIR) : le suivi propose désormais les trois modes du logiciel du contrôleur SteppIR — à chaque changement de fréquence, au-delà d un pas de 25/50/100 kHz, ou seulement au changement de bande. Les installations existantes conservent le mode par pas qu elles avaient déjà."
     ]
   },
   {