feat(uploader): add ryzencdn local-disk uploader (POST multipart + GET serve)

Shirokami-API source uploads to Ryzumi S3 (s3.ryzumi.vip) which is DNS-dead
from this VPS. Implemented a local-disk uploader keeping the source's response
shape {success, url, fileName, size}:
- POST /uploader/ryzencdn (multipart 'file' field, magic-byte ext detection)
- GET /uploader/file/{name} (path-traversal safe, MIME by extension)
Files stored under /var/lib/scraper/uploads (owned by scraper user).

src/application/mod.rs

@@ -8,4 +8,5 @@ pub mod proxy;
 pub mod search;
 pub mod stalk;
 pub mod tools;
+pub mod uploader;
 pub mod weebs;