feat(misc): add misc endpoints (currency-converter, harga-emas, kurs-bca, server-info)

Ported from Shirokami-API scraper/misc/*.js:
- /misc/currency-converter (wise.com scrape, amount/from/to)
- /misc/harga-emas (harga-emas.org Antam table)
- /misc/kurs-bca (bca.co.id jual/beli)
- /misc/server-info (OS/CPU/RAM/disk from /proc)

Also: remove /download/tiktok/v2 + /download/twitter/v2 as separate routes;
douyin.wtf + twitsave now internal fallback steps in the primary
fetch_tiktok/fetch_twitter chains (v2 = fallback per user directive).

src/presentation/router.rs

@@ -252,18 +252,27 @@ pub fn build_router(app_state: Arc<AppState>) -> anyhow::Result<Router> {
             "/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),
         )
+        // Misc routes
+        .route(
+            "/misc/currency-converter",
+            axum::routing::get(crate::presentation::handler::misc::currency_converter_handler),
+        )
+        .route(
+            "/misc/harga-emas",
+            axum::routing::get(crate::presentation::handler::misc::harga_emas_handler),
+        )
+        .route(
+            "/misc/kurs-bca",
+            axum::routing::get(crate::presentation::handler::misc::kurs_bca_handler),
+        )
+        .route(
+            "/misc/server-info",
+            axum::routing::get(crate::presentation::handler::misc::server_info_handler),
+        )
         // Health
         .route(
             "/health",