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/presentation/handler/mod.rs

@@ -9,4 +9,5 @@ pub mod proxy;
 pub mod search;
 pub mod stalk;
 pub mod tools;
+pub mod uploader;
 pub mod weebs;

src/presentation/handler/uploader.rs

@@ -0,0 +1,58 @@
+//! Axum handlers for the uploader.
+//!
+//! POST /uploader/ryzencdn — multipart file upload, saved to local disk.
+//! GET  /uploader/file/:name — serve an uploaded file.
+
+use axum::body::Body;
+use axum::extract::{Multipart, Path};
+use axum::http::{header, StatusCode};
+use axum::response::Response;
+use axum::Json;
+use serde_json::Value;
+
+use crate::application::uploader as use_cases;
+use crate::presentation::error::AppError;
+
+/// POST /uploader/ryzencdn — accept a multipart file upload.
+pub async fn ryzencdn_handler(mut multipart: Multipart) -> Result<Json<Value>, AppError> {
+    // Read the first file field.
+    let mut file_name = String::from("");
+    let mut data: Vec<u8> = Vec::new();
+
+    while let Some(field) = multipart
+        .next_field()
+        .await
+        .map_err(|e| AppError::BadRequest(format!("multipart: {e}")))?
+    {
+        let name = field.name().unwrap_or("file").to_string();
+        if name == "file" {
+            file_name = field.file_name().unwrap_or("").to_string();
+            let content = field
+                .bytes()
+                .await
+                .map_err(|e| AppError::BadRequest(format!("bytes: {e}")))?;
+            data = content.to_vec();
+            break;
+        }
+    }
+
+    if data.is_empty() {
+        return Err(AppError::BadRequest(
+            "No file field named 'file' in multipart body".into(),
+        ));
+    }
+
+    let result = use_cases::upload(&data, &file_name)?;
+    Ok(Json(result))
+}
+
+/// GET /uploader/file/:name — serve an uploaded file.
+pub async fn serve_file_handler(Path(name): Path<String>) -> Result<Response<Body>, AppError> {
+    let (bytes, mime) = use_cases::serve(&name)?;
+    Ok(Response::builder()
+        .status(StatusCode::OK)
+        .header(header::CONTENT_TYPE, mime)
+        .header(header::CACHE_CONTROL, "public, max-age=86400")
+        .body(Body::from(bytes))
+        .unwrap())
+}

src/presentation/router.rs

@@ -382,6 +382,15 @@ pub fn build_router(app_state: Arc<AppState>) -> anyhow::Result<Router> {
             "/image/brat/animated",
             axum::routing::get(crate::presentation::handler::image::brat_animated_handler),
         )
+        // Uploader routes
+        .route(
+            "/uploader/ryzencdn",
+            axum::routing::post(crate::presentation::handler::uploader::ryzencdn_handler),
+        )
+        .route(
+            "/uploader/file/{name}",
+            axum::routing::get(crate::presentation::handler::uploader::serve_file_handler),
+        )
         // Health
         .route(
             "/health",