Cut CPU use and move heavy work off the UI thread

Redraws:
- Merge bursts of session and bandmap events into one redraw
  (Coalesced). Closed Bandmap and Available windows now unsubscribe.
- Grayline and Voice Keyer no longer subscribe to the session twice.
- Available summary, Score table and Log rows redraw only when their
  contents change. Telnet lines are added in batches.
- Bandmap view reuses its layout, shaped text and brushes. Grayline
  draws the coastlines as one cached shape.

Threads:
- Available, Bandmap colours, Check and Statistics do their judging
  and counting on the thread pool and draw the result on the UI thread.
- ContestLog takes a lock in Judge and in each method that changes the
  log, so a background Judge cannot read the indexes mid-edit.

Refresh rate:
- Statistics refreshes every 30 seconds and when the QSO count changes.
- Grayline refreshes at most every 15 seconds on session events.

Publish with ReadyToRun to cut startup JIT time.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

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

@@ -32,7 +32,6 @@ public sealed partial class VoiceKeyerWindow : RefreshableWindow
         RecordBox.LostFocus += (_, _) => SaveCommands();
         PttBox.IsCheckedChanged += (_, _) => SaveCommands();
         OperatorBox.SelectionChanged += (_, _) => Refresh();
-        session.Changed += (_, _) => Dispatcher.UIThread.Post(Refresh);
         FillOperators();
         Refresh();
     }