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Auto-call is withdrawn — it duplicated DXHunter, which already answers decodes,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.

frontend/src/style.css

@@ -991,6 +991,18 @@
 @layer base {
   * { @apply border-border; }
   html, body, #root { height: 100%; }
+  /* No rubber-band, and no swipe-to-navigate.
+
+     Chromium lets a scroll that has reached the end pull the content a few
+     pixels and spring back, and a two-finger horizontal swipe means "go back a
+     page". Both are browser behaviours that have no meaning in a logbook: the
+     first makes a table wobble at the bottom of a list, and the second can
+     navigate the WebView away from the app entirely — a blank window and a
+     restart. Neither shows up with a mouse, which is why they went unnoticed;
+     they arrive with a precision touchpad or a touchscreen.
+
+     A no-op wherever the effects don't occur. */
+  html, body { overscroll-behavior: none; }
   /* Root rem base. Tailwind sizing (text/heights/padding/gaps) is in rem, so
      this is the single global density knob — shrinks the whole UI uniformly
      while Leaflet maps (px-based) stay correct. Default browser base is 16px. */
@@ -1055,3 +1067,15 @@
   filter: invert(1) brightness(1.8);
   opacity: 0.9;
 }
+
+/* Every scrollable pane keeps its overscroll to itself.
+
+   "contain" (not "none") on the inside: the pane still scrolls normally, it
+   simply stops passing the leftover motion up to its parent — which is how
+   scrolling a grid to its end used to tug the panel behind it. */
+.overflow-auto,
+.overflow-y-auto,
+.overflow-x-auto,
+.overflow-scroll {
+  overscroll-behavior: contain;
+}