Fix import: use exact filename stem as Eagle name field

Eagle matches metadata.json "name" to the actual filename stem exactly.
Prettifying names (replacing hyphens, stripping numbers) caused Eagle to
show empty folders. Also add Python import script (replaces bash version).

import_masterclass.py

@@ -195,7 +195,7 @@ def main():
         try:
             ext = filepath.suffix.lower().lstrip(".")
             stem = filepath.stem
-            display_name = clean_name(stem)
+            display_name = stem  # Must match filename stem exactly for Eagle to find the file
             item_id = gen_id()
             item_dir = IMAGES / f"{item_id}.info"
             item_dir.mkdir(parents=True, exist_ok=True)