Initial commit: terminal Minesweeper in C# for .NET 10

A playable console Minesweeper (arrow keys, chording, flags, question marks,
pause, difficulty presets) plus a deduction-and-guess solver that can play the
game headlessly. Game logic lives in src/Minesweeper/Game and has no console
dependencies, so it is covered by 65 unit tests.

Includes publishing helpers for self-contained, trimmed single-file binaries
(publish.sh) and an .editorconfig that the sources conform to: UTF-8 BOM and
4-space indents for C#, 2-space indents for project files, LF endings and
2-space indents for shell scripts, System-first usings, no redundant `this.`,
and s_/ _ prefixed private static and instance fields.

tests/Minesweeper.Tests/SolverTests.cs

@@ -0,0 +1,72 @@
+using Minesweeper.Game;
+using Xunit;
+
+namespace Minesweeper.Tests;
+
+public class SolverTests
+{
+    [Fact]
+    public void AnEmptyMinefieldIsClearedInOneGo()
+    {
+        var game = new MinesweeperGame(new Board(5, 5, 0), new Random(1));
+        var result = new Solver(game, new Random(2)).Run();
+
+        Assert.Equal(GameStatus.Won, result.Status);
+        Assert.Equal(25, game.RevealedCount);
+        Assert.Equal(0, result.Guesses);
+    }
+
+    [Fact]
+    public void TheStepBudgetStopsTheSearch()
+    {
+        var game = new MinesweeperGame(new Board(16, 16, 40), new Random(3));
+        var result = new Solver(game, new Random(4), maxSteps: 1).Run();
+
+        Assert.Equal(1, result.Steps);
+        Assert.Equal(GameStatus.Playing, game.Status);
+    }
+
+    [Fact]
+    public void TheSameSeedPlaysTheSameGame()
+    {
+        var first = Play(21, out var firstGame);
+        var second = Play(21, out var secondGame);
+
+        Assert.Equal(first.Status, second.Status);
+        Assert.Equal(firstGame.RevealedCount, secondGame.RevealedCount);
+        Assert.Equal(first.Guesses, second.Guesses);
+    }
+
+    [Fact]
+    public void DeductionsClearMostBeginnerBoards()
+    {
+        var wins = 0;
+        for (var seed = 1; seed <= 10; seed++)
+        {
+            if (Play(seed, out _).Status == GameStatus.Won)
+                wins++;
+        }
+
+        Assert.True(wins >= 8, $"expected the solver to win at least 8 of 10 beginner boards, won {wins}");
+    }
+
+    [Fact]
+    public void SolverNeverLeavesAHiddenSafeSquareBehind()
+    {
+        for (var seed = 1; seed <= 5; seed++)
+        {
+            Play(seed, out var game);
+            if (game.Status != GameStatus.Won)
+                continue;
+
+            Assert.Equal(game.TotalSafeCells, game.RevealedCount);
+        }
+    }
+
+    private static SolverResult Play(int seed, out MinesweeperGame game)
+    {
+        var random = new Random(seed);
+        game = new MinesweeperGame(new Board(9, 9, 10), random) { ReserveSafeZone = true };
+        return new Solver(game, random).Run();
+    }
+}