Add pc/ — PyInstaller build scripts, .ico icon, and README

pc/build.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# Cross-platform PyInstaller build (run from pc/ on any OS)
+set -euo pipefail
+cd "$(dirname "$0")"
+
+pip install pyinstaller
+
+python -m PyInstaller \
+    --onefile \
+    --name Kanjin \
+    --icon=kanjin.ico \
+    --distpath=. \
+    --workpath=build_temp \
+    ../main.py
+
+rm -rf build_temp __pycache__ Kanjin.spec
+
+echo ""
+echo "Done! Deliver pc/Kanjin.exe to players."