Fix get_applications_path() returning None on Mac

Return /Applications on macOS instead of calling Windows-only function.
This fixes a crash in app_framework's is_portable() check.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ctoth

platform_utils/paths.py

@@ -212,5 +212,7 @@ def start_file(path: str) -> None:
 
 
 def get_applications_path() -> Optional[str]:
-    """ """
+    """Return the system applications directory."""
+    if is_mac:
+        return "/Applications"
     return _winpaths.get_program_files()