Lay the band panel out the way N1MM lays it out, and colour it

N1MM's band panel is a row per band and a column per mode the contest runs,
with every cell painted by what the callsign being typed would be worth there:
red for one new multiplier, green for more than one, blue for points, grey for
a station already worked on that band and mode. With nothing typed every cell
is grey. That is the panel's point — it says where a station is still needed
without working the bands one at a time — and this had only the frame.

BandPanel holds the rule and is unit-tested without a window. The bands are the
six contest bands, with 30, 17 and 12 metres added for general logging: in N1MM
that is the one entry of the hundred and thirty-five that shows the WARC bands,
so Contest.ShowsWarcBands says so and GeneralLogging overrides it. The columns
are the modes the contest runs, so CQ WW CW has one column and IARU has two,
rather than always showing CW and phone. A digital entry gets one DIG column
where N1MM has RTTY and PSK: dupes and points here go by mode category, and
those two are the same category.

The labels are N1MM's: the metres alone up to 10, then the unit from 6m up. The
band the radio is on is ringed rather than filled, as N1MM rings it, so the
ring does not hide the colour underneath. The cells are labels with a click
handler rather than buttons, so the theme cannot paint over the colour under
the pointer.

Text on a filled cell is black or white by N1MM's rule: light is the three
channels adding up to more than 384.

Looked at under Xvfb in CQ WW CW: one CW column, six bands, grey with nothing
typed, and with a JA typed red on every band but 20, where the zone and country
are already claimed, and which carries the ring.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RoGtneMQaz4M9w7Kk49AVD

src/Nonemm.App/Windows/EntryWindow.axaml.cs

@@ -39,7 +39,6 @@ public sealed partial class EntryWindow : Window
         this.radioNumber = radioNumber;
         InitializeComponent();
         BuildFunctionKeys();
-        BuildBandButtons();
         session.Changed += (_, _) => Dispatcher.UIThread.Post(Refresh);
         session.ContestChanged += (_, _) => Dispatcher.UIThread.Post(() =>
         {