refactor(download): remove ProviderCore/download.py, move sanitize_filename to SYS.utils, replace callers to use API.HTTP.HTTPClient

scripts/debug_import_vimm.py

@@ -0,0 +1,9 @@
+import importlib, traceback
+
+try:
+    m = importlib.import_module('Provider.vimm')
+    print('Imported', m)
+    print('Vimm class:', getattr(m, 'Vimm', None))
+except Exception as e:
+    print('Import failed:', e)
+    traceback.print_exc()