feat: wire videy + tiktok/v2 + twitter/v2 downloader endpoints

Ported all missing downloader endpoints from Shirokami-API source
(verified against /home/code/Shirokami-API/scraper/downloader/):

- /download/videy: direct CDN link build (cdn.videy.co/{id}.mp4|.mov)
  matches videy.js exactly (id.len()==9 && id[8]=='2' -> .mov)
- /download/tiktok/v2: douyin.wtf hybrid API w/ fallback to embed scrape
- /download/twitter/v2: twitsave.com HTML scrape w/ fallback to Syndication API
- detect_platform now recognizes videy.co
- download_all_in_one dispatches videy

fetch_videy already existed as dead code (never wired); connected it.
== all others (bilibili/danbooru/dood/gdrive/instagram/kfiles/mediafire/
== mega/pinterest/pixeldrain/savetube/soundcloud/spotify/terabox/threads/
== tiktok/twitter/youtubeV2) already mapped to their Rust equivalents

src/application/downloader.rs

@@ -119,6 +119,18 @@ pub async fn download_streamable(url: &str) -> Result<DownloadResult, ScrapingEr
     DownloaderRepository::download_streamable(url).await
 }
 
+pub async fn download_videy(url: &str) -> Result<DownloadResult, ScrapingError> {
+    DownloaderRepository::download_videy(url).await
+}
+
+pub async fn download_tiktok_v2(url: &str) -> Result<DownloadResult, ScrapingError> {
+    DownloaderRepository::download_tiktok_v2(url, None).await
+}
+
+pub async fn download_twitter_v2(url: &str) -> Result<DownloadResult, ScrapingError> {
+    DownloaderRepository::download_twitter_v2(url, None).await
+}
+
 pub async fn download_bilibili(url: &str) -> Result<DownloadResult, ScrapingError> {
     DownloaderRepository::download_bilibili(url).await
 }
@@ -165,6 +177,8 @@ pub fn detect_platform(url: &str) -> String {
         "dailymotion".to_string()
     } else if url.contains("streamable.com") {
         "streamable".to_string()
+    } else if url.contains("videy.co") {
+        "videy".to_string()
     } else if url.contains("bilibili.com") || url.contains("b23.tv") {
         "bilibili".to_string()
     } else {

src/infrastructure/repository/downloader.rs

@@ -451,6 +451,7 @@ impl DownloaderRepository {
                 Err(_) => Self::download_facebook(url, cookies).await,
             },
             "tiktok" => Self::download_tiktok(url, cookies).await,
+            "videy" => Self::download_videy(url).await,
             "youtube" => match Self::download_youtube(url, "720").await {
                 ok @ Ok(_) => ok,
                 Err(_) => Self::download_youtube_mp3(url).await,
@@ -608,6 +609,33 @@ impl DownloaderRepository {
         fetch_streamable(url).await
     }
 
+    /// Videy video (direct CDN link build; ported from Shirokami-API videy.js).
+    pub async fn download_videy(url: &str) -> Result<DownloadResult, ScrapingError> {
+        fetch_videy(url).await
+    }
+
+    /// TikTok v2 (douyin.wtf hybrid API; falls back to embed scrape when dead).
+    pub async fn download_tiktok_v2(
+        url: &str,
+        cookies: Option<&str>,
+    ) -> Result<DownloadResult, ScrapingError> {
+        match fetch_tiktok_v2(url).await {
+            ok @ Ok(_) => ok,
+            Err(_) => Self::download_tiktok(url, cookies).await,
+        }
+    }
+
+    /// Twitter v2 (twitsave.com scrape; falls back to Syndication API when blocked).
+    pub async fn download_twitter_v2(
+        url: &str,
+        cookies: Option<&str>,
+    ) -> Result<DownloadResult, ScrapingError> {
+        match fetch_twitter_v2(url).await {
+            ok @ Ok(_) => ok,
+            Err(_) => Self::download_twitter(url, cookies).await,
+        }
+    }
+
     /// Bilibili video via b23.tv short link expansion.
     pub async fn download_bilibili(url: &str) -> Result<DownloadResult, ScrapingError> {
         fetch_bilibili(url).await

src/presentation/handler/downloader.rs

@@ -219,6 +219,30 @@ pub async fn download_streamable(
     Ok(Json(DownloadResponse::ok(result)))
 }
 
+/// Handler for _videy.
+pub async fn download_videy(
+    Query(params): Query<DownloadParams>,
+) -> Result<Json<DownloadResponse>, AppError> {
+    let result = use_cases::download_videy(&params.url).await?;
+    Ok(Json(DownloadResponse::ok(result)))
+}
+
+/// Handler for _tiktok_v2.
+pub async fn download_tiktok_v2(
+    Query(params): Query<DownloadParams>,
+) -> Result<Json<DownloadResponse>, AppError> {
+    let result = use_cases::download_tiktok_v2(&params.url).await?;
+    Ok(Json(DownloadResponse::ok(result)))
+}
+
+/// Handler for _twitter_v2.
+pub async fn download_twitter_v2(
+    Query(params): Query<DownloadParams>,
+) -> Result<Json<DownloadResponse>, AppError> {
+    let result = use_cases::download_twitter_v2(&params.url).await?;
+    Ok(Json(DownloadResponse::ok(result)))
+}
+
 /// Handler for _bilibili.
 pub async fn download_bilibili(
     Query(params): Query<DownloadParams>,

src/presentation/router.rs

@@ -248,6 +248,18 @@ pub fn build_router(app_state: Arc<AppState>) -> anyhow::Result<Router> {
             "/download/streamable",
             axum::routing::get(crate::presentation::handler::downloader::download_streamable),
         )
+        .route(
+            "/download/videy",
+            axum::routing::get(crate::presentation::handler::downloader::download_videy),
+        )
+        .route(
+            "/download/tiktok/v2",
+            axum::routing::get(crate::presentation::handler::downloader::download_tiktok_v2),
+        )
+        .route(
+            "/download/twitter/v2",
+            axum::routing::get(crate::presentation::handler::downloader::download_twitter_v2),
+        )
         .route(
             "/download/bilibili",
             axum::routing::get(crate::presentation::handler::downloader::download_bilibili),