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

Pecan-Brown Butter Trout.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/pecan-brown-butter-trout.webp
 ---
 title: Pecan-Brown Butter Trout
 servings: 2
@@ -9,6 +8,7 @@ source: Unknown
 description: Pan-seared trout with pecan-brown butter sauce, served with herbed sweet potatoes, radishes, and wilted greens
 prep_time: 30 minutes
 cook_time: 30 minutes
+image: https://roux.roo.lol/recipe-images/pecan-brown-butter-trout.webp
 ---
 
 Preheat #oven{} to 400°F.