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

cauliflower-milanese.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/cauliflower-milanese.webp
 ---
 title: Cauliflower Milanese
 source: https://cooking.nytimes.com/recipes/1026145-cauliflower-milanese
@@ -11,6 +10,7 @@ totalTime: 55 minutes
 prepTime: 15 minutes
 cookTime: 40 minutes
 tags: arugula, bread crumb, budget, cauliflower, parmesan, sheet-pan, fall, vegetarian
+image: https://roux.roo.lol/recipe-images/cauliflower-milanese.webp
 ---
 
 == Ingredients ==