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

BUTTERNUT & TURKEY CHILI with sweet peppers, spiced pepitas & queso fresco.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/butternut-turkey-chili-with-sweet-peppers-spiced-pepitas-queso-fresco.webp
 ---
 title: BUTTERNUT & TURKEY CHILI with sweet peppers, spiced pepitas & queso fresco
 servings: 1
@@ -10,6 +9,7 @@ tags:
   - butternut squash
   - chili
   - turkey
+image: https://roux.roo.lol/recipe-images/butternut-turkey-chili-with-sweet-peppers-spiced-pepitas-queso-fresco.webp
 ---
 
 Heat ~{1%Tbsp} @olive oil{} in a #pot over medium heat.