Add classic eye image assets and import scripts

- Generate 18 classic eye variants in 3 styles (realistic, anime, cartoon)
  with 6 colors each (blue, green, brown, hazel, grey, amber)
- Add scripts for generating, converting, and importing eyes:
  - generate_classic_eyes_ppm.py: Generate PPM images (no dependencies)
  - download_classic_eyes.py: Full-featured generator with PIL
  - startup_import_eyes.py: Import eyes on backend startup
  - import_saved_eyes.py: Import from saved directory
- Update docker-compose to mount scripts directory
- Include metadata.json for tracking eye properties

docker-compose.yml

@@ -11,6 +11,7 @@ services:
     volumes:
       - ./data:/app/data
       - ./backend:/app
+      - ./scripts:/scripts
     environment:
       - DATABASE_URL=sqlite:///./data/ai_photo_edit.db
       - SECRET_KEY=${SECRET_KEY:-change-this-secret-key-in-production}