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

Kung Pao Shrimp with Sichuan Roasted Green Beans.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/kung-pao-shrimp-with-sichuan-roasted-green-beans.webp
 ---
 title: Kung Pao Shrimp with Sichuan Roasted Green Beans
 servings: 2
@@ -7,6 +6,7 @@ tags: chinese,garnish-and-gather,kung pao,shrimp
 source: Unknown
 description: 
 prep_time: 25 minutes
+image: https://roux.roo.lol/recipe-images/kung-pao-shrimp-with-sichuan-roasted-green-beans.webp
 ---
 
 Preheat #oven{} to 425°.