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

Gaja's Bulgogi Lettuce Wraps.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/gaja-s-bulgogi-lettuce-wraps.webp
 ---
 title: Gaja's Bulgogi Lettuce Wraps
 servings: 2
@@ -7,6 +6,7 @@ tags: bulgogi,garnish-and-gather,korean,lettuce wraps
 source: Unknown
 description: 
 prep_time: 20 minutes
+image: https://roux.roo.lol/recipe-images/gaja-s-bulgogi-lettuce-wraps.webp
 ---
 
 Pat @steak bulgogi{8 oz} dry.