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

Chickpea Butter Curry.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/chickpea-butter-curry.webp
 ---
 title: Chickpea Butter Curry
 servings: 2
@@ -9,6 +8,7 @@ source: Unknown
 description: A vegetarian curry with chickpeas, cauliflower, and coconut milk, served with spiced oil drizzle
 prep_time: 20 minutes
 cook_time: 20 minutes
+image: https://roux.roo.lol/recipe-images/chickpea-butter-curry.webp
 ---
 
 In a small #pot{}, bring 1 1/2 cups @water{} & @basmati rice{3/4 cup} to a boil, then cover, reduce heat to low, and cook ~{12-15 minutes} or until @rice{} is tender.