feat(sat): the Satellites tab laid out again, and a visible ground track

Everything asked for and not delivered last time.

The sky plot moves to its own column on the LEFT of the map. It was
stacked in the readout column, where a plot that wants to be square
competed for width with the numbers and pushed the pass table off the
bottom of the screen — while the margin on the other side of the map sat
empty throughout. Its own width, dragged from its right edge, with
double-click to reset.

Every block of the readout column gets a heading and a chevron: the
pass, the position, what to tune, the pass list. Each remembers its own
state, because an operator working FM birds never looks at the linear
passband and one watching a schedule never looks at the range rate.
There were no headings at all before, which cost twice — nothing said
what a group of numbers was, and there was nowhere to put the control
that shuts it. A shut block keeps the one number it exists for in its
heading, and drops that badge again when open rather than repeating the
body a line below.

The tune panel now leads with the CENTRE of the passband. The
Doppler-corrected figure was the wrong number for a reference panel: it
moves every second, it is different for every operator, and it is not
what the frequency plan, the AMSAT tables or anybody on the air calls
the satellite's frequency. What the radio is actually on belongs beside
Tracking, where the radio is — it is already there — so this keeps the
correction only as the offset that explains the difference.

Badges rather than rows of grey words, in the app's own status tones, on
the things that decide something: the band of each frequency, the
Doppler offset, an inverting transponder, the passband width, and the
peak elevation of a pass.

And the ground track. It was `color: 'var(--info)'` on a map that
renders with preferCanvas, and a CSS variable is not a colour a canvas
strokeStyle can take — so the browser kept whatever was set last and the
track came out a pale near-white that vanished over the imagery and the
deserts alike. This is the same trap internal to GridSquareMap's own
comment: every other map in this app passes hex. Now a real colour over
a dark casing, the way a road is drawn, because one line cannot hold up
over both a pale sea and a dark continent but a line with an outline
can.

frontend/src/lib/i18n.tsx

@@ -607,6 +607,9 @@ const en: Dict = {
   'sat.antenna': 'Antenna', 'sat.rotCommanded': '(commanded — this controller does not report back)',
   'sat.aos': 'Rises in', 'sat.los': 'Sets in', 'sat.rise': 'Rise', 'sat.peak': 'Peak', 'sat.set': 'Set',
   'sat.range': 'Distance', 'sat.altitude': 'Altitude', 'sat.footprint': 'Footprint',
+  'sat.secWhere': 'Position', 'sat.secTune': 'Tune to', 'sat.skyWidthTip': 'Drag to resize the sky plot, double-click to reset it',
+  'sat.shiftHint': 'Doppler correction — the radio is on the centre frequency plus this. The corrected figure is beside Tracking.',
+  'sat.invertingHint': 'The passband is turned over: transmit on lower sideband to come back on upper.',
   'sat.tipEl': 'Elevation', 'sat.tipAz': 'Azimuth', 'sat.tipRange': 'Distance', 'sat.tipAlt': 'Altitude',
   'sat.tone': 'Tone', 'sat.toneHint': 'CTCSS on the uplink', 'sat.toneNone': 'no tone needed',
   'sat.rotAzOnly': 'azimuth only',
@@ -1230,6 +1233,9 @@ const fr: Dict = {
   'sat.antenna': 'Antenne', 'sat.rotCommanded': '(commandé — ce contrôleur ne répond pas)',
   'sat.aos': 'Lever dans', 'sat.los': 'Coucher dans', 'sat.rise': 'Lever', 'sat.peak': 'Culmination', 'sat.set': 'Coucher',
   'sat.range': 'Distance', 'sat.altitude': 'Altitude', 'sat.footprint': 'Empreinte',
+  'sat.secWhere': 'Position', 'sat.secTune': 'À accorder', 'sat.skyWidthTip': 'Glisser pour redimensionner le ciel, double-clic pour réinitialiser',
+  'sat.shiftHint': 'Correction Doppler — la radio est sur la fréquence centrale plus cette valeur. Le chiffre corrigé est à côté de Tracking.',
+  'sat.invertingHint': 'La bande passante est inversée : émettre en bande latérale inférieure pour revenir en supérieure.',
   'sat.tipEl': 'Élévation', 'sat.tipAz': 'Azimut', 'sat.tipRange': 'Distance', 'sat.tipAlt': 'Altitude',
   'sat.tone': 'Tonalité', 'sat.toneHint': 'CTCSS sur la montée', 'sat.toneNone': 'aucune tonalité requise',
   'sat.rotAzOnly': 'azimut seul',