v1.7.7: fix avvio Windows definitivo (rimuove Mark of the Web)

La causa root del "Failed to resolve Python.Runtime.Loader.Initialize"
era il Mark of the Web (Zone.Identifier ADS) che Windows aggiunge ai
file estratti da uno zip scaricato dal browser. .NET Framework
rifiuta SILENZIOSAMENTE di risolvere i symbol export degli assembly
managed con MOTW.

Fix multilivello:
- main.py: al primo avvio cancella :Zone.Identifier da ogni
  .dll/.exe/.pyd nel bundle (via ctypes kernel32.DeleteFileW)
- CI: Unblock-File su dist/ pre-zip
- requirements: pythonnet==3.0.5 + clr-loader==0.2.7.post0 pinnati

Vedi: https://github.com/r0x0r/pywebview/issues/1215
      https://github.com/pyinstaller/pyinstaller/issues/7412

requirements.txt

@@ -5,4 +5,5 @@ mutagen>=1.47.0
 pyobjc-core>=10.0 ; sys_platform == "darwin"
 pyobjc-framework-Cocoa>=10.0 ; sys_platform == "darwin"
 pyobjc-framework-WebKit>=10.0 ; sys_platform == "darwin"
-pythonnet==3.0.3 ; sys_platform == "win32"
+pythonnet==3.0.5 ; sys_platform == "win32"
+clr-loader==0.2.7.post0 ; sys_platform == "win32"