Rename script to music_cards_generator.py and update references

- Renamed generate_hitster_cards.py to music_cards_generator.py
- Updated all documentation references to use the new filename
- Removed remaining Hitster references from the filename
- Script name now matches the Music Cards branding

🤖 Generated with [Claude Code](https://claude.ai/code)

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

README.md

@@ -33,7 +33,7 @@ pip install spotipy reportlab qrcode[pil] pillow
 
 ### Basic Usage (Separate PDFs)
 ```bash
-python generate_hitster_cards.py \
+python music_cards_generator.py \
   --playlist "https://open.spotify.com/playlist/YOUR_PLAYLIST_ID" \
   --client-id YOUR_CLIENT_ID \
   --client-secret YOUR_CLIENT_SECRET \
@@ -43,7 +43,7 @@ python generate_hitster_cards.py \
 
 ### Single Interleaved PDF (for Duplex Printing)
 ```bash
-python generate_hitster_cards.py \
+python music_cards_generator.py \
   --playlist "https://open.spotify.com/playlist/YOUR_PLAYLIST_ID" \
   --client-id YOUR_CLIENT_ID \
   --client-secret YOUR_CLIENT_SECRET \