Add CW keying, function key messages and the documentation

The function keys send through cwdaemon or a WinKeyer, with N1MM's message
macros. Escape stops sending.

Settings are read with the reflection serializer rather than a generated one:
the generated one hands back null for every property the file leaves out
instead of the value the property is declared with, which crashed the program
the first time a new setting was added.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/Nonemm.App/Configuration/Settings.cs

@@ -1,5 +1,4 @@
 using System.Text.Json;
-using System.Text.Json.Serialization;
 using Nonemm.Core;
 
 namespace Nonemm.App.Configuration;
@@ -35,6 +34,27 @@ public sealed record Settings
 
     public IReadOnlyList<string> NetworkPeers { get; init; } = [];
 
+    /// `none`, `cwdaemon` or `winkeyer`.
+    public string KeyerKind { get; init; } = "none";
+
+    public string KeyerHost { get; init; } = "127.0.0.1";
+
+    public int KeyerPort { get; init; } = 6789;
+
+    public string KeyerSerialPort { get; init; } = "";
+
+    public int KeyerSpeed { get; init; } = 28;
+
+    /// The twelve function key messages, keyed F1 to F12.
+    public IReadOnlyList<string> CwMessages { get; init; } = [];
+
+    public IReadOnlyList<string> PhoneMessages { get; init; } = [];
+
+    /// Reflection rather than a generated serializer: the generated one hands
+    /// back null for every property the file leaves out instead of the value
+    /// the property is declared with.
+    private static readonly JsonSerializerOptions Json = new() { WriteIndented = true };
+
     public static Settings Load(string path)
     {
         if (!File.Exists(path))
@@ -43,8 +63,7 @@ public sealed record Settings
         }
         try
         {
-            return JsonSerializer.Deserialize(File.ReadAllText(path), SettingsJson.Default.Settings)
-                ?? new Settings();
+            return JsonSerializer.Deserialize<Settings>(File.ReadAllText(path), Json) ?? new Settings();
         }
         catch (JsonException)
         {
@@ -55,7 +74,7 @@ public sealed record Settings
     }
 
     public void Save(string path) =>
-        File.WriteAllText(path, JsonSerializer.Serialize(this, SettingsJson.Default.Settings));
+        File.WriteAllText(path, JsonSerializer.Serialize(this, Json));
 }
 
 /// The operator's station as it is stored, kept separate from `StationInfo` so
@@ -111,7 +130,3 @@ public sealed record StoredStation
         Precedence = Precedence,
     };
 }
-
-[JsonSerializable(typeof(Settings))]
-[JsonSourceGenerationOptions(WriteIndented = true)]
-internal sealed partial class SettingsJson : JsonSerializerContext;