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

Blackened Shrimp and Gouda Grits.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/blackened-shrimp-and-gouda-grits.webp
 ---
 title: Blackened Shrimp & Gouda Grits
 servings: 2
@@ -8,6 +7,7 @@ tags: caesar salad,garnish-and-gather,seafood,shrimp and grits,southern
 source: Unknown
 description: Southern-style shrimp and grits with smoked gouda, served with a charred scallion kale caesar salad
 prep_time: 25 minutes
+image: https://roux.roo.lol/recipe-images/blackened-shrimp-and-gouda-grits.webp
 ---
 
 In a #pot{}, bring 3 cups @water{} & @salt{1/2 teaspoon} to a boil.