feat: panadapter spots that read, a CI-V link that survives, no auto-call

Panadapter spots are now worth reading. The comment carries the spotter, the
entity and the status in DXHunter's own shape — "CQ up 2 [F4BPO] [Franz Josef
Land] [New Slot]" — which needed two things nothing documents: SmartSDR splits
its command line on SPACES, so the words ran together until every space became
non-breaking; and it truncates past ~60 characters, so the cluster's own words
are trimmed first and the three brackets always survive. RBN column padding is
collapsed on the way in, or a preserved run of spaces opened a gap wide enough
to push the rest off screen.

"Already worked" means the CALLSIGN is in the log, not the entity: saying it of
a station never contacted was simply wrong. Each status can also be kept off the
panadapter entirely, and the WSJT-X decode spots obey the same switches — the
palette governs the panadapter, not one of the two things that feed it.

And the radio is no longer hammered: a spot whose frequency, colour and comment
are unchanged is not removed and redrawn. A busy skimmer feed re-spots the same
station every few seconds; one two-minute session sent 2128 adds, 88 of them for
a single callsign, and the display did not move a pixel for any of them.

CI-V, from an IC-7850 that kept killing JTDX: a reply the rig sent to another
controller on the same bus is no longer taken for ours, and a set_ptt, set_freq
or set_mode whose acknowledgement goes missing is verified by reading the rig
back instead of being reported as a failure. WSJT-X and JTDX answer a failed
command with a Rig Control Error and drop the link mid-over — 98 keyings, 6 lost
acknowledgements, 2 dropped connections in one session. The check waits 700 ms,
not the poll's 150: the rig has just failed to answer twice because it was
retuning, and a short probe would fail for the same reason.

Auto-call is withdrawn — it duplicated DXHunter, which already answers decodes,
and two programs deciding that from one shack key over each other. The library
is kept whole and dormant; a guard in App.tsx makes sure a stored preference
cannot key a transmitter whose switch no longer exists.

Also:
  - the log rotates while running, not only at startup: the CI-V trace left on
    wrote 416 MB and nothing would have stopped it before the disk did. Closing
    it now releases the crash file too — the runtime keeps its own duplicate.
  - the interface zoom announces itself, with a badge, a click back to 100% and
    a View menu; Ctrl+wheel and Ctrl+0 always worked and nothing said so.
  - no more elastic bounce, and no swipe-to-navigate out of the app.
  - Edit QSO: your own TX power and the contacted station's extended locator
    were saved and written back with no box to set them.
  - FT decodes: continents are a multiple choice; a compound MSHV message that
    answers two stations in one line is recognised as addressed to you.

internal/applog/rotate_test.go

@@ -0,0 +1,49 @@
+package applog
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// The log has to be bounded WHILE RUNNING, not only at startup. The CI-V wire
+// trace left on for a day wrote 416 MB, and nothing would have stopped it
+// before the disk did.
+func TestRotatesMidSession(t *testing.T) {
+	orig := maxLogBytes
+	maxLogBytes = 8 * 1024 // small, so the test costs milliseconds
+	defer func() { maxLogBytes = orig }()
+
+	dir := t.TempDir()
+	p, err := Init(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer Close()
+
+	line := strings.Repeat("x", 256)
+	for i := 0; i < 100; i++ { // ~25 KB: several times the limit
+		Printf("%s", line)
+	}
+
+	if _, err := os.Stat(p + ".1"); err != nil {
+		t.Fatalf("no previous generation kept: %v", err)
+	}
+	fi, err := os.Stat(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fi.Size() > maxLogBytes {
+		t.Fatalf("current log is %d bytes, over the %d limit — it did not roll over", fi.Size(), maxLogBytes)
+	}
+	// The new file says where the rest went: a log that starts mid-sentence with
+	// no explanation is how an operator concludes the app lost its history.
+	b, err := os.ReadFile(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(string(b), "continued from "+filepath.Base(p)+".1") {
+		t.Error("the new file does not point at the one it continues")
+	}
+}