feat(stalk): add github + youtube profile stalk endpoints

Ported from Shirokami-API scraper/stalk/{github,youtube}.js:
- /stalk/github (GitHub public API profile)
- /stalk/youtube (ytInitialData parse from /videos subpage:
  handles lockupViewModel (new), videoRenderer, gridVideoRenderer,
  shortsLockupViewModel; channel metadata + top-5 videos)

Also fix misc harga-emas main price to smallest-gram (1gr).

src/presentation/router.rs

@@ -273,6 +273,15 @@ pub fn build_router(app_state: Arc<AppState>) -> anyhow::Result<Router> {
             "/misc/server-info",
             axum::routing::get(crate::presentation::handler::misc::server_info_handler),
         )
+        // Stalk routes
+        .route(
+            "/stalk/github",
+            axum::routing::get(crate::presentation::handler::stalk::github_handler),
+        )
+        .route(
+            "/stalk/youtube",
+            axum::routing::get(crate::presentation::handler::stalk::youtube_handler),
+        )
         // Health
         .route(
             "/health",