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

sheet-pan-miso-chicken-with-radishes-and-lime.cook

@@ -1,4 +1,3 @@
-image: https://roux.roo.lol/recipe-images/sheet-pan-miso-chicken-with-radishes-and-lime.webp
 ---
 title: Sheet-Pan Miso Chicken With Radishes and Lime
 source: https://cooking.nytimes.com/recipes/1020988-sheet-pan-miso-chicken-with-radishes-and-lime
@@ -9,6 +8,7 @@ cuisine:
 servings: 4 servings
 totalTime: 45 minutes
 tags: chicken, chicken thigh, ghee, miso, radish, spring
+image: https://roux.roo.lol/recipe-images/sheet-pan-miso-chicken-with-radishes-and-lime.webp
 ---
 
 == Ingredients ==