feat(image): add brat + animated brat image generation

Ported from Shirokami-API scraper/image/brat.js (v2 path):
- /image/brat - static brat PNG via brat.siputzx.my.id API
- /image/brat/animated - animated brat GIF
Both return raw image bytes with proper Content-Type (image/png, image/gif)

src/application/mod.rs

@@ -1,6 +1,7 @@
 pub mod anime;
 pub mod anime2;
 pub mod downloader;
+pub mod image;
 pub mod komik;
 pub mod misc;
 pub mod proxy;