Show local spots in bold and name the computer that made them

A spot an operator put on a bandmap, here or on another computer, is
drawn in bold. Its hover text names the computer instead of the
spotter's callsign. A spot from another computer carries the name from
the ADDSPOT message.

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

tests/Nonemm.Spotting.Tests/SpotDescriptionTests.cs

@@ -59,4 +59,17 @@ public class SpotDescriptionTests
 
         Assert.Equal(expected, SpotDescription.Of(spot, At.AddSeconds(seconds)));
     }
+
+    [Fact]
+    public void ALocalSpotNamesTheComputerInsteadOfTheSpotter()
+    {
+        Spot spot = new(
+            Callsign.Parse("JA1XYZ"), Frequency.FromKilohertz(14_025), At, SpotSource.Operator,
+            "OK1ABC")
+        {
+            Computer = "SHACK-2",
+        };
+
+        Assert.Equal("14025.0 by SHACK-2, 41m ago", SpotDescription.Of(spot, Now));
+    }
 }