Refactor windowed mode and subprocess handling

Removed redundant windowed mode setup from main.py and simplified subprocess creation flags logic across core and GUI modules. Centralized subprocess creation flags usage, eliminated custom run_subprocess_hidden wrapper, and improved logging handler setup for better compatibility with windowed applications.

main.py

@@ -1,50 +1,4 @@
 import sys
-import os
-
-# Early detection and handling of windowed mode to prevent console window flicker
-def setup_windowed_mode():
-    """
-    Setup windowed mode handling to prevent console window flickering.
-    This must be called as early as possible in the application startup.
-    """
-    if getattr(sys, 'frozen', False):
-        # Running as compiled executable (PyInstaller)
-        if sys.stdout is None or sys.stderr is None:
-            # Windowed mode - completely suppress console output
-            import io
-            null_stream = io.StringIO()
-            if sys.stdout is None:
-                sys.stdout = null_stream
-            if sys.stderr is None:
-                sys.stderr = null_stream
-        else:
-            # Console mode but compiled - redirect to null to prevent window flicker
-            if os.name == 'nt':  # Windows
-                try:
-                    import io
-                    # Create a null output stream
-                    null_stream = io.StringIO()
-                    # Only redirect if we detect this might cause console window issues
-                    # Check if we're not already in a console
-                    try:
-                        # Try to get console window handle - if this fails, we're likely windowed
-                        import ctypes
-                        kernel32 = ctypes.windll.kernel32
-                        console_window = kernel32.GetConsoleWindow()
-                        if console_window == 0:
-                            # No console window exists, redirect to prevent one from appearing
-                            sys.stdout = null_stream
-                            sys.stderr = null_stream
-                    except:
-                        # If console detection fails, err on the side of caution
-                        sys.stdout = null_stream
-                        sys.stderr = null_stream
-                except:
-                    # If all else fails, continue normally
-                    pass
-
-# Call windowed mode setup immediately
-setup_windowed_mode()
 
 from PySide6.QtWidgets import QApplication, QMessageBox