Refactor main application entry and enhance UI with file browser integration

- Changed application entry point to use QApplication for better compatibility with widgets.
- Set up QML UI style to support custom button backgrounds.
- Introduced LocalSettingsModel and FileBrowser for managing application settings and file selection.
- Updated QML components to reflect new data models and improve layout consistency.
- Enhanced Theme.qml with detailed comments and improved color management for better readability.

main.py

@@ -1,16 +1,36 @@
 import sys
 from pathlib import Path
 
-from PySide6.QtGui import QGuiApplication
 from PySide6.QtQml import QQmlApplicationEngine
+from PySide6.QtQuickControls2 import QQuickStyle
+from PySide6.QtWidgets import QApplication
 
+from backend.local_settings_model import LocalSettingsModel
+from backend.file_browser import FileBrowser
+
+# ===== Application Entry Point =====
 if __name__ == "__main__":
+    # ===== UI Style Setup =====
+    # Use a non-native controls style so our custom QML button backgrounds are supported.
+    QQuickStyle.setStyle("Basic")
+
+    # ===== Qt Bootstrap =====
     # Minimal Qt bootstrap: load the ISC QML module and exit if it fails.
-    app = QGuiApplication(sys.argv)
+    app = QApplication(sys.argv)
     engine = QQmlApplicationEngine()
+
+    # ===== Shared Models =====
+    settings_model = LocalSettingsModel()
+    select_file_dialog_model = FileBrowser()
+    settings_model.loadSettings()
+    engine.rootContext().setContextProperty("settingsModel", settings_model)
+    engine.rootContext().setContextProperty("file_browser", select_file_dialog_model)
+
+    # ===== QML Startup =====
     engine.addImportPath(Path(__file__).parent)
     engine.loadFromModule("ISC", "Main")
 
+    # ===== Exit Handling =====
     if not engine.rootObjects():
         sys.exit(-1)