feat(stalk): add mobile-legends, free-fire, genshin, twitter, tiktok, instagram

Ported from Shirokami-API scraper/stalk/*.js:
- /stalk/mobile-legends (gempaytopup CSRF+POST)
- /stalk/free-fire (freefirecommunity API + field transform)
- /stalk/genshin-impact (enka.network __data.json)
- /stalk/twitter (fxtwitter API)
- /stalk/tiktok (rehydration JSON parse)
- /stalk/instagram (mollygram HTML scrape)

Upstream status: twitter/genshin verified working live (elonmusk 241M followers).
github+youtube verified earlier. tiktok WAF-blocked, instagram mollygram-captcha
blocked, mobile-legends gempaytopup changed POST->GET+JS (all upstream dead for
VPS IP; code faithful to source).

src/presentation/handler/stalk.rs

@@ -42,3 +42,76 @@ pub async fn youtube_handler(
     let result = use_cases::youtube(&username).await?;
     Ok((StatusCode::OK, Json(result)))
 }
+
+/// GET /stalk/mobile-legends?user_id=...&zone_id=... (aliases: userid, zoneid)
+pub async fn mobile_legends_handler(
+    Query(params): Query<StalkParams>,
+) -> Result<(StatusCode, Json<Value>), AppError> {
+    let user_id = params
+        .user_id
+        .or(params.userid)
+        .ok_or_else(|| AppError::BadRequest("Missing 'user_id' parameter".to_string()))?;
+    let zone_id = params
+        .zone_id
+        .or(params.zoneid)
+        .ok_or_else(|| AppError::BadRequest("Missing 'zone_id' parameter".to_string()))?;
+    let result = use_cases::mobile_legends(&user_id, &zone_id).await?;
+    Ok((StatusCode::OK, Json(result)))
+}
+
+/// GET /stalk/free-fire?user_id=... (alias: userid)
+pub async fn free_fire_handler(
+    Query(params): Query<StalkParams>,
+) -> Result<(StatusCode, Json<Value>), AppError> {
+    let user_id = params
+        .user_id
+        .or(params.userid)
+        .ok_or_else(|| AppError::BadRequest("Missing 'user_id' parameter".to_string()))?;
+    let result = use_cases::free_fire(&user_id).await?;
+    Ok((StatusCode::OK, Json(result)))
+}
+
+/// GET /stalk/genshin-impact?user_id=... (alias: userid)
+pub async fn genshin_handler(
+    Query(params): Query<StalkParams>,
+) -> Result<(StatusCode, Json<Value>), AppError> {
+    let user_id = params
+        .user_id
+        .or(params.userid)
+        .ok_or_else(|| AppError::BadRequest("Missing 'user_id' parameter".to_string()))?;
+    let result = use_cases::genshin(&user_id).await?;
+    Ok((StatusCode::OK, Json(result)))
+}
+
+/// GET /stalk/twitter?username=...
+pub async fn twitter_handler(
+    Query(params): Query<StalkParams>,
+) -> Result<(StatusCode, Json<Value>), AppError> {
+    let username = params
+        .username
+        .ok_or_else(|| AppError::BadRequest("Missing 'username' parameter".to_string()))?;
+    let result = use_cases::twitter(&username).await?;
+    Ok((StatusCode::OK, Json(result)))
+}
+
+/// GET /stalk/tiktok?username=...
+pub async fn tiktok_handler(
+    Query(params): Query<StalkParams>,
+) -> Result<(StatusCode, Json<Value>), AppError> {
+    let username = params
+        .username
+        .ok_or_else(|| AppError::BadRequest("Missing 'username' parameter".to_string()))?;
+    let result = use_cases::tiktok(&username).await?;
+    Ok((StatusCode::OK, Json(result)))
+}
+
+/// GET /stalk/instagram?username=...
+pub async fn instagram_handler(
+    Query(params): Query<StalkParams>,
+) -> Result<(StatusCode, Json<Value>), AppError> {
+    let username = params
+        .username
+        .ok_or_else(|| AppError::BadRequest("Missing 'username' parameter".to_string()))?;
+    let result = use_cases::instagram(&username).await?;
+    Ok((StatusCode::OK, Json(result)))
+}

src/presentation/router.rs

@@ -282,6 +282,30 @@ pub fn build_router(app_state: Arc<AppState>) -> anyhow::Result<Router> {
             "/stalk/youtube",
             axum::routing::get(crate::presentation::handler::stalk::youtube_handler),
         )
+        .route(
+            "/stalk/mobile-legends",
+            axum::routing::get(crate::presentation::handler::stalk::mobile_legends_handler),
+        )
+        .route(
+            "/stalk/free-fire",
+            axum::routing::get(crate::presentation::handler::stalk::free_fire_handler),
+        )
+        .route(
+            "/stalk/genshin-impact",
+            axum::routing::get(crate::presentation::handler::stalk::genshin_handler),
+        )
+        .route(
+            "/stalk/twitter",
+            axum::routing::get(crate::presentation::handler::stalk::twitter_handler),
+        )
+        .route(
+            "/stalk/tiktok",
+            axum::routing::get(crate::presentation::handler::stalk::tiktok_handler),
+        )
+        .route(
+            "/stalk/instagram",
+            axum::routing::get(crate::presentation::handler::stalk::instagram_handler),
+        )
         // Weebs routes
         .route(
             "/weebs/anime-info",