fix: correct YAML frontmatter, convert images to proper WebP format

- Moved image: field from outside to inside YAML frontmatter (50 files)
- Converted all 56 non-WebP images to proper WebP format via ImageMagick
- Fixed Python shebangs for portability
- Updated source fields in 2 Task 3 recipes

Baked Chile Relleno with Black Beans.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/baked-chile-relleno-with-black-beans.webp
 ---
 title: Baked Chile Relleno with Black Beans
 servings: 2
@@ -10,6 +9,7 @@ tags:
   - mexican
   - peppers
   - vegetarian
+image: https://roux.roo.lol/recipe-images/baked-chile-relleno-with-black-beans.webp
 ---
 
 Preheat the #oven to high broil with a rack near the broiler.