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

Barbecue Chicken with Crispy Pan-Fried Okra & Cheddar Biscuits.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/barbecue-chicken-with-crispy-pan-fried-okra-cheddar-biscuits.webp
 ---
 title: Barbecue Chicken with Crispy Pan-Fried Okra & Cheddar Biscuits
 servings: 2
@@ -10,6 +9,7 @@ tags:
   - chicken
   - biscuits
   - okra
+image: https://roux.roo.lol/recipe-images/barbecue-chicken-with-crispy-pan-fried-okra-cheddar-biscuits.webp
 ---
 
 Preheat the #oven to 400°F and lightly grease a #baking sheet.