build: Add PyInstaller standalone build scripts and app icon

.gitignore

@@ -28,3 +28,9 @@ desktop.ini
 
 # Logs
 *.log
+
+# App Config
+config.json
+
+# PyInstaller
+*.spec

build.py

@@ -0,0 +1,23 @@
+import PyInstaller.__main__
+import tkinterdnd2
+import os
+import shutil
+
+def build():
+    tkdnd_path = os.path.join(os.path.dirname(tkinterdnd2.__file__), 'tkdnd')
+    
+    # Ensure dist and build dirs are clean
+    if os.path.exists('dist'): shutil.rmtree('dist')
+    if os.path.exists('build'): shutil.rmtree('build')
+
+    PyInstaller.__main__.run([
+        'kobackupdec_gui.py',
+        '--name=KoBackupDecryptor',
+        '--onefile',
+        '--windowed',
+        '--icon=app.ico',
+        f'--add-data={tkdnd_path};tkinterdnd2/tkdnd'
+    ])
+
+if __name__ == '__main__':
+    build()

create_icon.py

@@ -0,0 +1,19 @@
+import sys
+from PIL import Image
+
+def create_ico(input_path, output_path):
+    img = Image.open(input_path)
+    # Crop to square if necessary
+    width, height = img.size
+    if width != height:
+        min_dim = min(width, height)
+        left = (width - min_dim) / 2
+        top = (height - min_dim) / 2
+        right = (width + min_dim) / 2
+        bottom = (height + min_dim) / 2
+        img = img.crop((left, top, right, bottom))
+    
+    img.save(output_path, format="ICO", sizes=[(256, 256), (128, 128), (64, 64), (32, 32), (16, 16)])
+
+if __name__ == "__main__":
+    create_ico(sys.argv[1], sys.argv[2])