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.

publish.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+# Builds self-contained, trimmed, single-file binaries for Linux and Windows.
+# Usage: ./publish.sh [linux-x64|win-x64|linux-arm64|win-arm64 ...]  (default: linux-x64 win-x64)
+set -euo pipefail
+
+cd "$(dirname "$0")"
+
+rids=("$@")
+if [ ${#rids[@]} -eq 0 ]; then
+  rids=(linux-x64 win-x64)
+fi
+
+for rid in "${rids[@]}"; do
+  out="artifacts/$rid"
+  echo "==> publishing $rid"
+  dotnet publish src/Minesweeper \
+    --configuration Release \
+    --runtime "$rid" \
+    --self-contained true \
+    -p:PublishTrimmed=true \
+    -p:PublishSingleFile=true \
+    -p:IncludeNativeLibrariesForSelfExtract=true \
+    -p:DebugType=none \
+    -p:DebugSymbols=false \
+    --output "$out"
+  binary="$out/minesweeper"
+  case "$rid" in
+    win-*) binary="$binary.exe" ;;
+  esac
+  du -h "$binary" | sed 's/^/    /'
+done
+
+echo "done - binaries are under artifacts/<runtime>/"