Improve console suppression for windowed mode on Windows

Refactored console window suppression logic to better handle PyInstaller windowed applications and prevent console flicker. Added creation flags and redirected subprocess streams in multiple modules to ensure hidden console windows when running subprocesses. Introduced a utility function for running subprocesses with hidden console and updated all relevant subprocess calls to use it.

src/gui/ytsage_gui_main.py

@@ -1,5 +1,6 @@
 import json
 import subprocess
+import sys
 import threading
 import webbrowser
 from pathlib import Path
@@ -1735,7 +1736,21 @@ class YTSageApp(QMainWindow, FormatTableMixin, VideoInfoMixin):  # Inherit from
 
             # Execute command with hidden console window on Windows
             # Extra logic moved to src\utils\ytsage_constants.py
-            result = subprocess.run(cmd, capture_output=True, text=True, timeout=60, creationflags=SUBPROCESS_CREATIONFLAGS)
+            creation_flags = SUBPROCESS_CREATIONFLAGS
+            if getattr(sys, 'frozen', False):
+                # Running as compiled executable - use additional flags to prevent console flicker
+                creation_flags |= subprocess.CREATE_NEW_PROCESS_GROUP | subprocess.DETACHED_PROCESS
+            
+            result = subprocess.run(
+                cmd, 
+                capture_output=True, 
+                text=True, 
+                timeout=60, 
+                creationflags=creation_flags,
+                stdin=subprocess.DEVNULL,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.PIPE
+            )
 
             if result.returncode != 0:
                 raise Exception(f"yt-dlp failed: {result.stderr}")