feat(sat): generate the frequency plan, and join on the catalog number

25 satellites, typed by hand and never revisited. Eight of them were the
first-generation Tevel constellation, which re-entered in 2024; four more had
come down too; and the nine Tevel-2 satellites that replaced them, the Chinese
space station, AO-27, AO-123 and twenty others were simply absent. So: 44
satellites now, and a generator instead of a memory.

cmd/satgen joins three public sources on the NORAD catalog number — Celestrak's
amateur group and PE0SAT's mirror for which birds OpsLog can actually get
elements for, and SatNOGS DB for the transmitters. It is a one-shot tool, run by
hand, the same arrangement as cmd/cntygen, and it is deliberately conservative:

  - It never destroys a curated entry. The hand-written plans hold things
    SatNOGS does not reliably carry — a CTCSS tone, the QO-100 passband as
    operators describe it — so an existing bird keeps its data and only gains
    its catalog number.
  - It prunes on the re-entry date, which is a fact SatNOGS publishes rather
    than a judgement about which of the missing satellites are missing for good.
  - It refuses a digital uplink that does not say what it is. A GMSK uplink is a
    command channel far more often than a digipeater, and shipping the wrong one
    invites somebody to transmit on a control frequency. An analog uplink with
    both ends is a contact by construction, which is what catches the repeaters
    that describe themselves only as "Mode V/U FM".
  - Its output is deterministic. One satellite can hold two catalog entries —
    GreenCube is 53106 in one feed and 53109 in the other — and iterating a map
    picked a different one each run.

A bird now carries its NORAD number, and that is how its elements are found.
Names were the only join before, and they are written differently by every party
involved: "TIANYAN 01" and "TO-108" are one satellite that had never once met,
so TO-108 tracked nothing at all.

And the plan now reaches a station that has already run OpsLog. The editable
copy was written on the first launch and was the operator's list for ever after,
so a release adding nine satellites reached nobody who had opened the tab. It is
merged on each load instead: a satellite they already have is untouched, edits
and corrections included, and only the ones they have never seen are added.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

app_sat.go

@@ -622,6 +622,11 @@ func (a *App) GetSatelliteNames() []string {
 // The feed's name and the operator's name for the same satellite are routinely
 // different, and the element set is keyed by the feed's.
 func satElement(store *sat.Store, b sat.Bird) (sat.Element, bool) {
+	// The catalog number first: it is exact, and it is what the generated plan
+	// carries. Everything below is for the hand-written entries that have none.
+	if e, ok := store.GetNORAD(b.NORAD); ok {
+		return e, true
+	}
 	if e, ok := store.Get(b.Name); ok {
 		return e, true
 	}