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

Korean Shrimp Tacos.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/korean-shrimp-tacos.webp
 ---
 title: Korean Shrimp Tacos
 servings: 2
@@ -9,6 +8,7 @@ source: Unknown
 description: Crispy shrimp tacos with gochujang sauce and bok choy rice salad
 prep_time: 25 minutes
 cook_time: 25 minutes
+image: https://roux.roo.lol/recipe-images/korean-shrimp-tacos.webp
 ---
 
 In a #pot{}, bring 1 1/2 cups @water{} & @salt{1/4 teaspoon} to a boil.