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

Thai_Veggie_Pad_See_Ew.cook

@@ -1,9 +1,9 @@
-image: https://roux.roo.lol/recipe-images/thai-veggie-pad-see-ew.webp
 ---
 title: Thai Veggie Pad See Ew
 servings: 2
 category: Thai
 source: Unknown
+image: https://roux.roo.lol/recipe-images/thai-veggie-pad-see-ew.webp
 ---
 
 Bring water to a boil for rice noodles.