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

Spicy Shrimp Paella.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/spicy-shrimp-paella.webp
 ---
 title: Spicy Shrimp Paella
 servings: 2
@@ -9,6 +8,7 @@ tags:
   - paella
   - shrimp
   - spanish
+image: https://roux.roo.lol/recipe-images/spicy-shrimp-paella.webp
 ---
 
 In a large sauté #pan, cook @chorizo{2%oz} over medium for ~{3-5%minutes}, until cooked through, then remove, keeping drippings in the pan.