refactor: reorganize project structure and move examples

- Move examples (Blackjack, TicTacToe) to the root directory
- Convert example projects from Console applications to Libraries
- Add Directory.Build.props for shared build settings
- Update solution file and project references to reflect new paths

Blackjack/Singletons/GamePhase.cs

@@ -0,0 +1,10 @@
+namespace Blackjack;
+
+public enum GamePhase : byte
+{
+    Betting = 0,
+    Dealing = 1,
+    PlayerTurn = 2,
+    DealerTurn = 3,
+    RoundOver = 4
+}

Blackjack/Singletons/GameState.cs

@@ -0,0 +1,17 @@
+using MessagePack;
+
+namespace Blackjack;
+
+/// <summary>
+/// Global game state stored on the singleton entity.
+/// </summary>
+[MessagePackObject]
+public struct GameState
+{
+    [Key(0)] public GamePhase Phase;
+    [Key(1)] public RoundResult Result;
+    [Key(2)] public int Chips;
+    [Key(3)] public int CurrentBet;
+    [Key(4)] public int RoundNumber;
+    [Key(5)] public uint Seed;
+}

Blackjack/Singletons/RoundResult.cs

@@ -0,0 +1,12 @@
+namespace Blackjack;
+
+public enum RoundResult : byte
+{
+    None = 0,
+    PlayerBust = 1,
+    DealerBust = 2,
+    PlayerWin = 3,
+    DealerWin = 4,
+    Push = 5,
+    Blackjack = 6
+}